Royal guard holding vigil by Queen's coffin faints

A royal guard standing vigil by the Queen's coffin at Westminster Hall in London collapsed in front of mourners paying their final respects to the late sovereign.

The guards are holding a 24-hour vigil in six-hour shifts as mourners file past in the 900-year-old hall to pay their respects to Queen Elizabeth II as she lies in state.

The shifts normally rotate about every 20 minutes.

READ MORE: What to know about the Queen's lying in state in Westminster

Footage showed the solemn silence being broken as the guard - a member of the Royal Company of Archers holding a long bow - collapsed to the stone floor on Wednesday night GMT (Thursday AEST) from the podium where he was standing.

The incident drew shocked reactions from the mourners present.

Police officers immediately rushed to his aid and he was taken away for treatment.

The Royal Company of Archers is a ceremonial military unit that protects the monarch in Scotland.

Earlier, a member of the Royal Family collapsed as the Queen's coffin made its way from Buckingham Palace to Westminster Hall.

EXPLAINED: What we know about Queen Elizabeth II's funeral

Lady Gabriella Windsor fainted on seeing the coffin, reports UK magazine Hello!

Lady Windsor is the daughter of Prince Michael of Kent, the Queen's first cousin and shared a special bond with the late Monarch.

The publication also reported the socialite was not seen for the rest of the ceremony.

The Queen will lie in state at Westminster until the morning of her funeral on Monday, September 19, to allow the public to pay their respects to Britain's longest reining monarch.

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