William and Harry will not walk shoulder to shoulder behind their grandfather's coffin when he is laid to rest tomorrow. The estranged brothers are both in the small party of close family members who will follow the Duke of Edinburgh's body. But they will be separated by their cousin, Peter Phillips. And when the coffin is carried into St George's Chapel in Windsor, William will move ahead of his younger brother as they take their seats separately. The extraordinary turn of events will be seen by some as a missed opportunity to show family unity in the wake of Prince Philip's death. Others questioned whether the princes were being kept apart deliberately at their own request. But a Buckingham Palace spokesman said: 'This is a funeral [and] we will not be drawn into those perceptions of drama. The arrangements have been agreed and reflect Her Majesty's wishes.' It came as details of Philip's royal ceremonial funeral, which will take place at 3pm tomorrow, were publicly released. These included: The Queen will wear a mask, sit socially-distanced from her family and follow the coffin of her husband of 73 years in the state Bentley; The 30-strong congregation comprises of all of Philip's children and grandchildren, their spouses and close relatives including Princess Margaret's son the Earl of Snowdon; The only non-family member of the group is his close friend and carriage driving companion Countess Mountbatten of Burma, Penny Knatchbull; Other royals including the Duchess of Kent have not been invited after Covid rules meant a 1,000-name list was whittled down; The Land Rover hearse specially designed by the duke to carry his coffin was unveiled. William and Harry, 36, were last seen in public together at a Commonwealth Day service in March last year where they could barely look each other in the eye following Harry and Meghan's acrimonious split from the Royal Family. Relations were further soured by the couple's explosive interview with Oprah Winfrey last month, in which they attacked senior royals while Philip, who died on Friday aged 99, lay in hospital. It had been quietly hoped that the loss of their beloved grandfather, who both men loved deeply, might start the process of rapprochement. Tomorrow is likely to be particularly difficult for the brothers as it will evoke memories of having to walk behind their mother's coffin when they were just 15 and 13. But today royal biographer Hugo Vickers said that Peter Phillips, Philip's eldest grandson, may have been deliberately chosen to help his two younger cousins find a way forward with their relationship, which has become badly strained in the past year. He said: 'Peter Philips was incredibly good with the boys when Diana died, so I think it will be very good for them. Sometimes I think that when people behave very well in public, which I think they will do, they find it easier to behave better in private. Prince Philip and the Queen were conciliators all their life so I'm sure that is what he would have wanted'. William and Harry, 36, were last seen in public together at a Commonwealth Day service in March last year where they could barely look each other in the eye following Harry and Meghan's acrimonious split from the Royal Family Harry and William will not stand together at Prince Philip's funeral on Saturday, unlike them doing so at their mother Princess Diana's funeral (pictured) The Land Rover Defender hearse that will carry Philip's coffin is seen for the first time as it is driven into Windsor Castle today Queen Elizabeth and the Duke of Edinburgh are pictured last year in the quadrangle of Windsor Castle ahead of his 99th birthday Philip's medals include the following.