Statistics on rate of Vehicle Excise Duty (VED, or road tax) evasion among vehicles seen on UK roads, and the associated revenue loss.
In 2017, we see that an estimated 1.8% of vehicles in traffic on roads in the UK were unlicensed. The increase is probably largely due to changes to the vehicle licensing system which were introduced in October 2014 and April 2017.
VED evasion at the levels estimated in 2017 could have cost about 100 million pounds in lost revenue in the UK. Some of this revenue will have been recovered through DVLA enforcement activity or through vehicle keepers back-licensing their vehicles.