The Duke of Sussex joined his brother, Prince William in wearing military uniform.
Harry, who saw action on the front line during two tours of duty in Afghanistan, has previously been denied the chance to wear his military uniform as he publicly mourns, because he is no longer a working royal.
But King Charles III decided his youngest son could wear uniform for the vigil – and Harry could be seen standing proud at the foot of his grandmother's coffin.
The Prince of Wales stood at the head, while the two brothers were flanked by cousins Zara Tindall, Peter Philips, Princesses Beatrice, Princess Eugenie, Lady Louise Windsor and her brother James, Viscount Severn.
Despite being a former Army officer, Harry has been in civilian dress for official events, including walking behind Queen Elizabeth II's coffin on Wednesday.
The Duke of Sussex wore a Blues and Royals No 1 Uniform, KCVO Neck Order and Star, Afghanistan Operational Service Medal, Golden, Diamond and Platinum Jubilee medals and Army Pilot Wings.
Queen Elizabeth II's grandchildren took part in a vigil on Saturday at Westminster Hall.
GB News
Other family members watched on from the sidelines during the vigil, among them The Earl and Countess of Wessex.
William was followed in by Harry, with the Duke of York’s daughters, the Earl of Wessex’s children and the Princess Royal’s children behind them.
The Queen’s eight grandchildren looked deep in thought as they stood guard around her coffin for a vigil in Westminster Hall.
They had their heads bowed as members of the public filed past them.
The Prince of Wales led his brother the Duke of Sussex
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William wore the Blues and Royals No 1 uniform, the Garter Sash, the Garter Star, the Golden, Diamond and Platinum Jubilee Medals and RAF pilot wings.
On Friday evening, the late monarch's children – the King, Prince Andrew, Princess Anne and Prince Edward – took part in their own vigil.
Queen Elizabeth II's grandchildren took part in a vigil on Saturday at Westminster Hall.
GB News
Prince Harry had his head bowed as members of the public filed past.
GB News
The four siblings had solemn looks on their faces as they stood with their heads bowed throughout as members of the public filed slowly past them.
It comes as final preparations are under way for the funeral on Monday, with politicians and royal dignitaries from around the world expected to arrive throughout the weekend.
On Saturday, Prime Minister Liz Truss will meet the prime ministers of Australia and New Zealand – Anthony Albanese and Jacinda Ardern – at the Government’s Chevening country residence, a No 10 spokesperson said.
Charles will also meet chiefs of staff at Buckingham Palace on Saturday and visit police headquarters to thank the emergency services for their work in planning the funeral.
On Sunday, Ms Truss will meet Irish Taoiseach Micheal Martin, Canadian premier Justin Trudeau, Polish President Andrzej Duda and US President Joe Biden at Downing Street.
She will have an audience with the King before attending his reception for visiting heads of state at Buckingham Palace on Sunday.
Charles concluded his tour of the home nations on Friday, starting his day with a visit to Wales, after trips to Northern Ireland and Scotland in recent days.
Prince Harry wore a morning suit during the walk behind Queen Elizabeth II's coffin on Wednesday
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