Joe Biden may have to take the bus to Queen’s funeral with other VIPs as ‘limos & helicopters banned’ amid high security

Instead they will leave their cars at a location in West London, be driven to the service and then shuttled back following a reception, leaked communications suggest.

One foreign ambassador based in London moaned on a WhatsApp message this morning: "Can you imagine Joe Biden on a bus?"

It comes after a no-fly zone was approved over the capital as authorities gear up for what is said to be the largest ever security operation in the UK.

Police snipers were spotted on rooftops as senior Her Majesty's coffin arrived in Edinburgh today watched by Princess Anne and Prince Andrew.

Meanwhile elite SAS troops are reportedly being deployed and 10,000 police officers will be on duty to throw a ring of steel around London next week.

MI6 and GCHQ spooks are also said to be working on security arrangements as 2,000 VIPs arrive for the funeral.

The leaked communication by the Foreign, Commonwealth and Development Office revealed world leaders have been asked to travel on commercial flights where possible.

Anyone who insists on travelling by private jet must land at smaller airports because Heathrow will be unavailable.

Helicopter transfers between airports and venues are also reportedly banned due to the number of flights operating at the time.

Only leaders and their spouse or partner will be invited due to limited space and they will be forced to leave their private state vehicles behind.

Those who cannot attend can nominate another official to go on their behalf.

The FCDO said in its communication 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".

It is not clear whether these rules will apply to Mr Biden and First Lady Jill.

One previous visits to Britain, US presidents have flown into Stansted airport on Air Force One.

They have then continued their journey on the Marine One chopper or bombproof "Beast" limousine accompanied by dozens of bodyguards.

Last year at the G7 summit in Cornwall, Mr Biden brought two giant limousines and 400 Secret Service agents.

The White House today confirmed Mr Biden and wife Jill will attend the funeral next Monday.

King Charles III will host a reception for all overseas leaders at Buckingham Palace on the evening before the funeral, the document also revealed.

They can visit the Queen lying in state and sign a condolence book at Lancaster House afterwards.

There they can also deliver tributes of up to three minutes which will be recorded for the media.

Foreign Secretary James Cleverley will be hosting their reception after the service.

Her Majesty's body arrived in Edinburgh this afternoon after leaving Balmoral for the last time.

She will lie in state from tomorrow evening at St Giles' Cathedral before travelling down to London.

Her body will then lie in state at Westminster Hall from Wednesday until the morning of her funeral.