The former monarch's coffin has made the journey from St Giles' Cathedral in Edinburgh.
People cheered “hip hip hooray” after the coffin drove under the arch.
Many people lining the street put down their umbrellas as a sign of respect while some could be seen wiping tears from their eyes.
Phone camera lights lit up the crowds as people documented the historic moment.
The hearse was moved directly to Edinburgh Airport, where a guard of honour found by the Royal Regiment of Scotland received the coffin with a royal salute.
It was then flown via a Royal Air Force aircraft and taken to RAF Northolt, accompanied on the journey by Princess Anne.
Queen Elizabeth II's coffin was then moved to Buckingham Palace, via the A40, before it was received by The King's Guard – who formed a guard of honour on its arrival.
Queen Elizabeth II's coffin after the flight from Edinburgh Kirsty Wiggelsworth
Queen Elizabeth II's coffin being transferred to its hearse Andrew Matthews
It was taken to the Bow Room by The Queen’s Company, 1st Battalion Grenadier Guard, where it was placed on trestles in the centre of the room.
This arrival sequence was witnessed by King Charles III and Camilla, Queen Consort, along with other members of the Royal Family.
A rota of chaplains to the King, who were formerly appointed by Queen Elizabeth II, will keep watch over the coffin while it rests in the Bow Room.
Queen Elizabeth II was consulted on the plans prior to her death.
The State Hearse is finished in Royal Claret, the same colour as the official royal and state vehicles kept in the Royal Mews at Buckingham Palace, and used by members of the royal family on official duties.
The vehicle features Her Majesty's Personal Royal Cypher.
The state hearse has been designed to allow members of the public to have a clear view of Queen Elizabeth II’s coffin as it travels through London, as well as the capital and Windsor on Friday.
Queen Elizabeth II's coffin arriving at Buckingham Palace POOL