Devoted Princess Anne is making the poignant journey with the late Queen’s coffin from Scotland to London.
The Princess Royal and her husband Vice Admiral Sir Tim Laurence attended a prayer service at St Giles’ Cathedral in Edinburgh before leaving with the oak coffin just before 4.30pm.
Crowds lined the Royal Mile and well-wishers could be heard applauding in moving scenes.
At 6pm, the late Queen will depart Scotland for the last time accompanied by her daughter.
Anne was at Balmoral when her mother peacefully passed away aged 96 last Thursday. She made the emotional 180-mile journey behind the late Queen’s coffin from the castle on Royal Deeside to Edinburgh on Sunday.
The coffin will be flown this evening from Edinburgh Airport to London on an RAF Globemaster C-17 flight.
From there it will be transported to Buckingham Palace on a state hearse.
The King and Queen Consort will receive the coffin at the royal residence where the late Queen spent so many of her decades on the throne.
The Prince and Princess of Wales will also be at the Palace in central London.
A guard of honour formed of three officers and 96 soldiers from The King’s Guard will be mounted in the Quadrangle.
Military commands, usually shouted, will be given as quietly as possible in honour of the solemn occasion.
The coffin will be carried by a bearer party to the Bow Room where a sovereign’s piper will play a lament.
It will remain in the Bow Room overnight before a procession on Wednesday to Westminster Hall for the start of the lying in state.
Some 300 police officers are stationed on the roads surrounding RAF Northolt ahead of the arrival of the Queen’s coffin by plane there on Tuesday evening.
One officer is stood per 20 yards as part of security arrangements, as huge crowds are expected to watch the flight from the roads, the RAF has said.
Members of the public are already queueing for the Queen’s lying in state which opens tomorrow.
Earlier today, Charles visited Northern Ireland with Camilla as part of his Operation Spring Tide tour around the UK.
The King and Queen Consort touched down in Belfast before travelling to Hillsborough Castle in Co Down, the royal residence in Northern Ireland, for several engagements.
They held a private audience with the new Northern Ireland Secretary Chris Heaton-Harris, as well as meeting representatives of political parties in the region.
The couple then received a message of condolence on behalf of the people of Northern Ireland from the speaker of the Stormont Assembly Alex Maskey.
They went on to a reception at the castle, hosted by Mr Heaton-Harris, which some members of the public also attended.
Charles and Camilla then travelled to St Anne’s Cathedral in Belfast where they attended a service of reflection for the life of the Queen.
The King and Queen Consort ended the packed visit with a walkabout at Writers’ Square.
On Monday, both Houses of Parliament gathered at Westminster Hall in London to express their condolences to Charles.
He later travelled north of the border and led members of the Royal Family in a procession in Edinburgh behind the Queen’s coffin from the Palace of Holyroodhouse to St Giles’ Cathedral.
The late Queen’s coffin stood on public view in the place of worship for 24 hours with thousands of people solemnly walking past to pay their respects to the nation’s longest-reigning monarch.