Foreign leaders attending the Queen's funeral will be packed into coaches and taken together to Westminster Abbey, according to official documents seen by Politico.
The heads of state and their spouses have also been advised to arrive in the UK on commercial flights and have been banned from using their own helicopters and cars.
The protocol for the service on Monday, September 19, is very particular and only leaders and their partners are invited from each country being represented.
It means US President Joe Biden and his wife Dr Jill Biden may opt not to fly over on Air Force One.
And they certainly can't use private helicopter Marine One once in Britain or arrive at the Abbey in the presidential Cadillac - The Beast.
For the latest updates as the world mourns the Queen and King Charles III's reign begins, follow our live blog.
Instead, they will be shoulder to should with fellow leaders on a bus which will collect them all from an undisclosed location in west London.
An official document from the UK Foreign Office says "because of tight security and road restrictions" they must leave their own cars and use the coaches supplied.
The protocol, sent out to overseas embassies on Saturday night and seen by POLITICO, said it “regrets that, because of limited space at the state funeral service and associated events, no other members of the principal guest’s family, staff or entourage may be admitted.”
However, any heads of state who cannot attend can choose another official rep to go in their place.
King Charles III will host a reception for the visiting leaders at Buckingham Palace after the funeral.
The overseas dignitaries will also be able to view the Queen's body as it lies in state and sign a condolence book.
They will then also be invited to deliver a recorded tribute lasting up to three minutes at Lancaster House.
A second FCDO document detailing logistical arrangements goes on to say: “Multiple and comprehensive layers of security will be in place across London and at all the official venues used for the state funeral and associated events."
After the funeral, leaders will walk across the Abbey grounds to a reception held by new Foreign Secretary James Cleverly.
They will then return to the coaches to be taken back to their cars.
The paperwork adds that "where possible", those attending should arrive in the UK on commercial flights as London Heathrow will not be available for private aircraft to land.
However, those who insist on using private planes are told to land at "less busy" airports.
* This weekend, the Daily Mirror and Sunday Mirror celebrate the life of Her Majesty the Queen with a commemorative special filled with all the key moments from Britain’s longest reigning monarch.
Be sure to pick up your copy of the Daily Mirror and Sunday Mirror to get both pullouts.
