Prince William and Harry walk together for Queen's procession, as they did for mother's 25 years ago

Prince William and Harry walked side by side behind The Queen's coffin, as they did 25 years ago following the tragic death of their mum, Princess Diana. Watch here:

The Queen’s coffin has been carried from Buckingham Palace to Westminster Hall, and the brothers marched solemnly behind as mourners lined the streets.

The coffin is draped with the Royal Standard and adorned with the glittering, priceless Imperial State Crown on a purple velvet cushion and a wreath of white flowers for the procession to the lying in state.

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The flowers are white roses, spray white roses, white dahlias and foliage, including pine from the gardens at Balmoral and pittosporum, lavender and rosemary from the gardens at Windsor.

The coffin was borne on a Gun Carriage of The King’s Troop Royal Horse Artillery – poignantly used for the coffins of the late Queen’s mother and father.

Known as the George Gun Carriage, it carried King George VI from Sandringham Church to Wolferton Station after his death in 1952 and was used in the funeral of the Queen Mother in 2002.

BBC

The Gun Carriage has six 13-pounder quickfire guns, built between 1913 and 1918, all of which have seen active service in the First and Second World Wars.

They are used regularly for royal salutes in Hyde Park, Green Park or Windsor Great Park for State Occasions and to mark royal anniversaries and royal birthdays.

Minute Guns – one for every 38 minutes of the procession – were fired from Hyde Park by The King’s Troop Royal Horse Artillery throughout the slow journey from Buckingham Palace.

Big Ben also tolled at one-minute intervals as the Queen left her London home for the last time.

The Imperial State Crown was the crown the Queen wore when she left Westminster Abbey after her coronation.

BBC

It was also used on other State occasions, including the State Opening of Parliament.

Made of gold, it is set with 2,868 diamonds, 17 sapphires, 11 emeralds, 269 pearls, and four rubies.

It contains some of the Crown Jewels’ most famous pieces including the Black Prince’s Ruby, the Stuart Sapphire, and the Cullinan II diamond.

As the Queen’s coffin entered Westminster Hall, the choir of Westminster Abbey and the choir of His Majesty’s Chapel Royal, St James’s Palace, sang Psalm 139.

The Archbishop of Canterbury then read the opening prayer, which the King appeared to follow through an order of service.

The Queen's coffin will now lie in state in Westminster Hall until the funeral on Monday (19 September).