Official Statistics

Quality and Methodology Information (QMI) for BDUK delivery performance, quarterly

Published 24 July 2025

1. About this report

This quality and methodology information report contains information on the quality characteristics of the data as well as the methods used to create it.

This report will help you to:

• Understand the strengths and limitations of the data
• Understand the methods used to create the data
• Decide suitable uses for the data
• Reduce the risk of misusing data

2. Contact

Organisation unit: Building Digital UK (BDUK)’s Analysis Function 

Responsible Statistician: M McMahon, Head of Reporting and Statistics 

Author: M Zottoli, Senior Statistical Officer

Email: statistics@bduk.gov.uk

Please contact us at the above email with any questions or suggestions for improvements.

3. Data and methods information

3.1 Data description

The data is used to produce BDUK’s performance reporting, which presents how many premises in the United Kingdom have received a gigabit-capable broadband connection as a result of BDUK subsidy.

3.2 Source data

We use a range of source data to produce these statistics. Further detail on management information sources for delivery data can be found in the Data collection section.

BDUK uses geographic data, including urban/rural postcode, and administrative area lookups from:

• Office for National Statistics (ONS)
• Northern Ireland Statistics and Research Agency (NISRA)
• Scottish Government

BDUK uses premises- and postcode-level data from Ofcom to estimate the number of premises that we have subsidised that are in Ofcom’s premises base. We use the most recent Connected Nations dataset available.

A list of the source data versions can be found in each release’s bulletin (for 2024 onwards).

3.3 Statistical unit

Unique Property Reference Number (UPRN): A unique identifier for an addressable location, used interchangeably with “premises”. This unique number does not change through time.

3.4 Statistical population

BDUK has its own list of premises that are deemed to be in scope for subsidy. These are based on Ordnance Survey (OS) AddressBase Premium classifications. The categories are designed to include only those locations where a gigabit-capable connection would provide benefit (e.g. dwelling or business). BDUK’s premises base is different from that used by Ofcom. Further details on comparisons with Ofcom’s data can be found in the Coherence and comparability section of this document.

For further details on the premises base, BDUK published the latest version of Premises in BDUK plans on 1 July 2025. This UPRN-level dataset provides a comprehensive view of broadband availability and delivery status across England and Wales, reflecting the most recent Open Market Review (OMR) data. It identifies whether each premises has gigabit access, is included in Project Gigabit, or is part of a supplier’s commercial rollout. To build on this, BDUK is working with the devolved administrations in Scotland and Northern Ireland to incorporate data from these regions into future versions of the dataset. 

Alternatively, you may contact the statistics production team at statistics@bduk.gov.uk for information on the classifications used.

3.5 Reference area

The geographic region covered by the data is the United Kingdom (UK).

3.6 Time coverage

Data covers the period between 1 April 2012 to 31 December 2024. Delivery of gigabit-capable connectivity commenced under the Superfast programme in 2012, but we have condensed all data for premises connected before 31 March 2021 into one category (“Before 2021/22”). Data are presented by financial year for financial years up to April 2024. Quarterly data are presented from April 2024 to December 2024.

3.7 Data collection  

Management information for the Gigabit Infrastructure Subsidy (GIS) intervention, also referred to as “Gigabit contracts”, is submitted monthly by suppliers to BDUK in incremental Stage 2 progress reports as spreadsheets through the Atamis contract management system. BDUK conducts a series of data quality checks on these reports and only documents that pass these checks are used for reporting.

Management information for the hubs intervention comes from different sources. For the Local Full Fibre Network (LFFN) and Rural Gigabit Connectivity (RGC) interventions, data is now sourced from two static and previously assured datasets, as the interventions have completed delivery and fully closed. For the hubs intervention, data is updated monthly by the project delivery team in a delivery tracker spreadsheet, which is manually checked by analysts.

Management information for the vouchers intervention comes through two sources. BDUK holds management information on which premises have been issued vouchers and where vouchers have been connected. We also hold information on vouchers projects, including the agreed list of expected premises passed. We additionally receive quarterly data from active vouchers suppliers (Ready For Service (RFS) data); this includes premises that have been passed as a result of the vouchers project intervention, but where occupiers have not claimed a voucher. We are aware of data quality issues with vouchers RFS data and only use data submissions that meet our quality checks for reporting purposes.

Management information for the Superfast programme is provided by suppliers on a quarterly basis through one of two routes: either to the local body with whom the Superfast contract is held, or directly to BDUK, where there is an arrangement to do so. These reports are cumulative and contain all delivery within that contract to date.

3.8 Data validation

For all interventions, each UPRN (if supplied) provided by suppliers is checked to ensure that it is a valid UK UPRN, has a valid passed date (the date the supplier provided delivery to that premises) and that the premises is eligible for BDUK subsidy and in the relevant contract.

3.9 Classification systems

We use multiple classification systems in our tables.

For table 3, we classify premises by geography using the April 2025 version of the Office for National Statistics’ (ONS) National Statistics UPRN Lookup (NSUL) and the February 2025 version of the National Statistics Postcode Lookup (NSPL) in conjunction with the Ordnance Survey’s AddressBase Premium product. We first attempt a full match on UPRN, then postcode, and finally string extraction from the address. Where none of these have been successful, the premises geography is defined as “Unknown”.

For table 8, we classify premises by BDUK intervention. Premises will only be counted in one intervention. Premises are removed from our counts where the premises have benefitted from more than one intervention, keeping the record with the earliest delivery date. The majority of these premises are related to overspill or indirect subsidy rather than BDUK directly paying to provide a connection to particular premises more than once.

For table 9, we use the Ofcom premises base. For transparency, BDUK has estimated how many of the premises passed by BDUK interventions also form part of the latest Ofcom Connected Nations ‘premises base’. This is the list of premises that Ofcom collect data on and the basis of their reporting of how many UK premises have access to a gigabit-capable service. Ofcom publishes details on their methodology for identifying their premises base.

BDUK interventions use different eligibility criteria from Ofcom’s premises base. Most notably, we include in scope of our subsidy ‘child’ premises (e.g. apartments in houses of multiple occupancy); Ofcom does not include the individual apartments. All other figures in the performance report reflect the full scope of our programmes rather than the Ofcom Connected Nations ‘premises base’. See the Statistical processing and data compilation section for more details on data quality and processing for this table.

For table 10, we count contractual premises as “built” when they have been delivered by our subsidised supplier in each lot/contract area. We only include initial and deferred scope premises. Note that there is no statistical processing for overspill or overbuild for these figures. Initial scope premises are planned for delivery at the start of the Gigabit Infrastructure Subsidy (GIS) contract. Deferred scope premises are premises that BDUK deemed to be potentially commercially viable at the point of contract signature; the intention is for these to be delivered after completion of the initial scope of the contract, if they are reclassified as gigabit “White” subsidy control status  (i.e. premises where there is no gigabit-capable broadband infrastructure and where they are not expected to receive such infrastructure commercially within the next three years).

3.10 Statistical concepts and definitions

Premises – a UPRN that is eligible for subsidy

Premises passed– premises are treated as passed by gigabit-capable broadband if it is possible to access a gigabit-capable service for the supplier’s standard price and be connected in the supplier’s standard timescale, and received this connection as a result of BDUK subsidy

Overspill – premises that were not directly funded but received connections as a result of nearby BDUK-funded projects

Overbuild - cases where a premises already has an approved gigabit-capable broadband from a commercial supplier (and BDUK is aware of this through its OMR) at the point in time that the BDUK-subsidised supplier builds the connection. This means that BDUK was not initially responsible for the premises becoming gigabit capable. Note that BDUK contracts are designed based on data about target premises at the point of invitation to tender, not on live delivery data and BDUK’s assured OMR data did not indicate that there was a credible commercial plan at the point of invitation to tender; it may not be practicable or possible to change plans if BDUK subsequently becomes aware of commercial delivery plans.

3.11 Statistical processing and data compilation

The data processing methodology for counting premises involves identifying and reporting premises that have received a gigabit-capable connection due to BDUK interventions. This includes both directly funded premises and those classified as overspill (see Statistical concepts and definitions).

The criteria for counting these overspill premises are:

• there must be intentional overspill delivery for the intervention
• BDUK must hold sufficient quality data to measure overspill
• premises must not have received a gigabit-capable connection without BDUK involvement at the time of contract award

All  BDUK’s interventions have measured intentional overspill delivery; this effect is largest for the vouchers and hubs interventions, which were specifically designed to encourage additional build beyond the premises we directly subsidise.

For Superfast, suppliers often built to additional premises en route to the directly subsidised premises; these are premises that they would not have otherwise built. Whether these premises are deemed to meet the overspill definition depends on the contract phase and the data available:       

• For Phase 1 and Phase 2 contracts (the initial phases of the programme which targeted 90% and 95% Superfast coverage by December 2016 and December 2017 respectively), all reported premises are counted as BDUK-delivered. This is because gigabit-capable coverage in the UK was below 2.5% at the time, making commercial delivery highly unlikely.
• For Phase 3 contracts (aimed at extending Superfast coverage beyond 95% by a target deadline of March 2025), BDUK only counts these reported premises as delivered if its cost model identifies them as uncommercial and if they are outside areas where Virgin Media O2 was expected to upgrade to gigabit-capable coverage.

For vouchers, the intervention is designed to subsidise uncommercial broadband build through demand aggregation. Suppliers are expected to deliver to all the premises within a project, but BDUK only funds those where the occupier takes a gigabit-capable service and claims a voucher. Each project includes a list of expected premises passed, covering both subsidised and non-subsidised premises. BDUK validates the UPRNs returned by suppliers and only counts those that its cost model identifies as uncommercial due to high costs. A 5% attrition rate, based on Ofcom data, is applied to confirm that premises have indeed been built.

As of the Delivery performance report quarterly: April 2024 to December 2024, 66% of all vouchers premises are counted using this methodology.

Where expected premises passed data is unavailable or of poor quality, BDUK applies a multiplier approach to estimate the number of additional uncommercial premises built per paid voucher. This method is based on completed projects with reliable data and calculates the average number of premises passed per voucher, adjusted by an 18% attrition rate to account for premises that were planned but not ultimately built. The multipliers vary by financial year:

Financial Year	Value of the multiplier
Before 2019/2020	2.1
2019/2020	2.2
2020/2021	2.1
2021/2022	1.8
After 2022/2023	1.7

This analysis was last updated in summer 2023. As of the Delivery performance report quarterly: April 2024 to December 2024, 34% of voucher premises are estimated using this method – primarily from older projects where high-quality data was not available.

As more data is submitted, the proportion of premises counted using each method may shift, since the calculation approach can be updated on a project-by-project basis.

For hubs, we currently report only the number of directly subsidised sites, but we plan to revise using a multiplier approach once our research evaluation into the effectiveness of hubs additionality (measuring the number of extra premises built as a result of the intervention) is published.

For GIS contracts, BDUK currently reports contracted premises as passed if they have been delivered and not overbuilt. Therefore, premises are excluded where there is evidence that another supplier had already built to them before the BDUK-subsidised supplier. As of December 2024, this has resulted in the removal of approximately 7,730 premises (around 12.5%) of the total delivered under GIS.  That is, of the 62,030 premises built by suppliers under our GIS contracts (Table 10), we have removed 7,730 premises due mostly to overbuild, resulting in a total of 54,300 premises passed by our GIS contracts (Table 8).

We deduplicate UPRNs within and across interventions so any UPRN is only reported once, keeping the record with the earliest verified date of delivery. Approximately 9,000 premises have been removed from our counts where the premises has been removed from more than one intervention. The majority of these (5,900, or 65%) are related to indirect subsidy (that is, where we count a premises as overspill), while the remaining 3,100 premises were removed due to overlaps involving direct subsidy, product-level deduplication or data inconsistencies such as legacy reporting errors.

For table 9, we are unable to exactly report the number of premises passed by BDUK that form part of the Ofcom premises base due to data gaps at UPRN level. To estimate the total number of Ofcom premises passed by BDUK we assume that this group of unknown premises have the same percentage split between Ofcom and wider premises as for the group where it is known, grouped by product and delivery year. We therefore estimate the premises passed within Ofcom’s premises base by calculating the percentage of verified premises passed UPRNs which are in the Ofcom premises base, stratified by product and delivery year, and then multiply this percentage by the total premises passed for that product and delivery year. These estimates are then summed to give the total estimated delivery in the Ofcom premises bases.

4. Quality characteristics

4.1 Quality management

BDUK’s quality assurance strategy sets out minimum standards for quality assurance for analytical products and documentation, as well as roles and responsibilities across the organisation. The quality assurance strategy meets the requirements of the Government Functional Standard for Analysis.

The official statistics releases are compiled by members of the government analytical professions in BDUK, under the guidance of the lead official for statistics at BDUK and the Head of Profession for Statistics at the Department for Science, Innovation and Technology (DSIT).

Decisions on data sources, analytical methods and assurance processes are agreed within the analytical team. This ensures decisions about the statistics are made by team members with appropriate professional capability, who can provide independent decision making and leadership.

Data is governed at BDUK by the Digital, Data and Technology team in line with GDPR and CDDO guidance on standards and best practice. Appropriate statistical disclosure rules are applied by analysts where confidential data is used.

4.2 Relevance

We classify our users into the main categories of industry bodies, interested local groups, and the general public. The statistics provided here are developed to meet the key requirements of all of these users. The bulletin is designed for the general public, our accessible spreadsheet tables contain information for interested local groups, and the upcoming full annual release will contain more information of interest to industry bodies and local government.

Shortcomings of our data content include the timeliness of our data (that it can take months after a premises is built for us to report that it has been built) and that we are unable to precisely compare our premises base to Ofcom’s. We also recognise that we are unable to precisely determine when a premises first received a gigabit-capable broadband connection, resulting in a likely overcount of premises where an unsubsidised supplier built to a premises commercially before BDUK’s subsidised supplier built.

We welcome user feedback on the usefulness and value of our statistics. We intend to run a consultation in 2026 to assess whether the tables published in the quarterly statistics meet user needs.

4.3 Confidentiality

Information published here is not confidential, except for vouchers issued as those relate to individuals taking up a gigabit-capable connection.

Statistical disclosure control is applied to confidential data in line with the Code of Practice for Statistics and relevant legislation.

4.4 Accessibility and clarity

Data is released through data tables (for professional users) and the text of the annual report and accounts (for both professional and occasional users). These data releases are freely available on GOV.UK and are designed to meet the Web Content Accessibility Guidelines (WCAG) 2.2 standard for web accessibility.

4.5 Accuracy and reliability

BDUK is aware of some accuracy issues with its data. These fall into two main categories: supplier error and matching where there is incomplete information.

Supplier error  

BDUK is aware of supplier errors, including missing and inaccurate information, in returns to BDUK. We believe these errors are infrequent but are working with our data teams to improve data assurance as our Gigabit contracts deliver more premises. These data errors generally affect data fields that do not directly drive subsidy payments but may be used in reporting (such as the date of build or the build plans for the infrastructure network).  

Incomplete information

BDUK’s data sometimes has incomplete information, especially for its older delivery programmes such as Superfast. For Superfast, there are approximately 7,000 premises where the local body has validated Superfast delivery but the supplier report does not hold the date the connection was provided. These premises passed have been attributed to delivery before 31 March 2021 because they were all delivered through Phase 1 and Phase 2 Superfast contracts.

We do not always have access to full UPRN data for our delivery, mainly affecting legacy reporting, and so must rely on postcode or other data to provide geographic information. In many cases we are able to match to higher levels of geography (e.g. region) but are unable to match to lower levels of geography (e.g. parliamentary constituency). A manual exercise was performed in 2023 to match null UPRNs to specific locations, but gaps remain where there is incomplete or invalid UPRN and postcode information. Where we do not have UPRN-level information and rely on postcodes, we apply a postcode cap. That is, the maximum number of premises we count in a postcode is the number of premises in BDUK’s premises base in that postcode.

BDUK has modelled data for the commerciality of a premises; that is, whether a premises is likely to receive a gigabit-capable connection as part of a commercial build project. As outlined in the Statistical processing and data compilation section, we use our own cost model to determine the relative commerciality of premises, which treats 18% of premises as uncommercial due to high costs. We also have incomplete data on which supplier has first built to a premises, making it challenging for us to determine whether the BDUK-subsidised supplier was the first to build to a premises.

Following the receipt of updated and more robust data from Superfast suppliers, BDUK has revised the premises count for this product upwards (by approximately 9,000 premises) between 1 April 2012 and 31 December 2024, relative to the BDUK Annual performance report for 2023 to 2024.

As we receive more RFS data, which in some cases relates to historical financial years, we are likely to have an increased number of premises with unknown speeds before intervention. This is because with older vouchers data, for which we use the multiplier approach, we apply the speed of the connected premises to the additional multiplied premises. With RFS data, we need to match to Ofcom speed data for each individual premises, which we do not have for every RFS premises.

4.6 Timeliness

BDUK has a time lag for its external reporting due to the time taken to receive data from suppliers, and the statistical production time. Superfast data has the longest time lag; the data arrives 20 working days after the quarter ends, and there are occasionally data issues that require manual cleansing or supplier clarification for issues such as rounded or invalid UPRNs and future delivery dates. Final data is expected 40 working days after quarter end.

BDUK is looking to improve the time lag in future by publishing quarterly. We aim to reduce our overall time lag to six weeks after the end of the quarter.  

4.7 Coherence and comparability

BDUK is unable to directly compare its data with Ofcom data for two main reasons:

• BDUK’s premises base differs from Ofcom’s premises base; the primary distinction is that our base includes “child” premises (e.g. apartments in houses of multiple occupancy) whereas Ofcom’s does not. As such, it is not possible to calculate BDUK’s contribution towards UK gigabit connectivity by taking the number of premises subsidised by BDUK and dividing by the size of Ofcom’s premises base.
• BDUK does not have access to UPRN-level data from Ofcom’s collections, meaning that we can only reliably look at postcode-level data from Ofcom to compare to our UPRN-level data.

BDUK’s data also cannot be compared directly with ThinkBroadband’s coverage estimates because their raw premises-level coverage data is not publicly available, and their premises base is not publicly defined.  

BDUK believes that its data, much of which is publicly released in our forward-looking Premises in BDUK plans datasets, is the best basis on which to judge its performance, but acknowledges that Ofcom’s Connected Nations data is the industry regulator’s view of progress in broadband rollout and that ThinkBroadband publishes more timely data than BDUK or Ofcom.

4.8 Cost and burden

We estimate that producing the first quarterly statistics release took about 50 days full time equivalent. We are seeking to improve efficiency through automating data pipelines, improving the clarity of requirements for supplier data submissions

4.9 Data revision

Revisions will be conducted under the Department for Science, Innovation and Technology (DSIT) revisions policy with the advice of the Head of Profession for Statistics at DSIT.