The siblings, whose parents are Princess Anne and Captain Mark Phillips, appeared alongside their six cousins for the vigil held at Westminster Hall. Zara stood in the lower right corner of the queen’s coffin, while Peter stood in the lower left.
During the wake, Zara stood next to Prince Harry, at the base of the coffin, and Lady Louise Windsor, the daughter of the Earl and Countess of Wessex.
Meanwhile, Peter stood next to James, the younger brother of Viscount Severn and Lad Louise, on the other side of the Duke of Sussex.
Prince William led the royal party into the room where the Queen lies before her funeral, after three strokes from a soldier’s sword.
The royal family stood in near silence, watching the passage of members of the public.
At around 6:15 p.m., three more rounds of the sword were heard and the Queen’s grandchildren came out.
Princess Anne’s children were last seen in the Queen’s procession on Wednesday on her final journey from Buckingham Palace.
During the ceremony, Zara was spotted shooting her husband, former rugby player Mike Tindall, a ‘look’ as he appeared to break the silence that had settled during the service.
Mail on Sunday deputy editor Kate Mansey said: “As the procession got closer we obviously couldn’t see it in the hall but we could hear the bells ringing and the drums coming closer and closer. over and inside the room there was complete silence.
“There was a moment of levity as Mike Tindall cleared his throat and Zara kind of gave him a look.”
The Queen’s grandchildren followed in the footsteps of their parents, who held a powerful vigil of a similar nature on Friday evening.
King Charles, the Princess Royal, Prince Andrew and the Earl of Wessex took part in the vigil as members of the public slowly filed past them.
Queues to view the Queen’s coffin as it lies in Westminster state have been miles long, with massive waits to enter.
King Charles and Prince William surprised royal mourners today as they made an impromptu stop near Lambeth Bridge to meet people in the queue.
Princes’ wakes are occasions when members of the royal family stand guard by a deceased monarch during their time in state.
This has happened before for King George V in 1936 and the Queen Mother in 2002 – but both occurrences only featured male members.
Zara, along with Lady Louise and Princesses Beatrice and Eugenie, made history tonight as the first granddaughter to stand guard.