The principals were invited to the UK as Guests of Her Majesty The Queen (State Visits) or Guests of Government at the invitation of the Prime Minister or Foreign Secretary.
For such visits the Foreign & Commonwealth Office (FCO) covers the cost of accommodation, transport, food and incidentals (to a set limit) in the UK for the Official Delegation (Principal plus a maximum of 10 ministers or senior officials) during the official programme only. Accommodation costs for one FCO Visit Officer are also paid. International air fares for the visiting delegation are the responsibility of the government concerned.
Costs for State and Guest of Government visits vary depending on the rank of the principal, the length of visit, numbers in the delegation and individual programme requirements. The Royal Family and UK ministers receive similar treatment on some visits overseas, when the host country covers the costs