The Duke of Edinburgh’s coffin will descend into the Royal Vault during his funeral service, lowered by an electric motor.
Joe Little, managing editor of Majesty magazine, described the moment as “unique in British royal history”.
Usually, the movement of the coffin into the vault beneath the floor of the Quire of St George’s Chapel would take place in private, Mr Little said.
It is not yet known whether the BBC’s television cameras will focus on the coffin at this moment, or move away to film buglers who will be honouring the duke, or other elements of the proceedings.
Joe Little, managing editor of Majesty magazine, told the PA news agency: “I think it will be unique in British royal history if the public get to see this on television.
“Clearly it’s an intimate moment, usually only witnessed by the royal family.
“I think it will be regarded as too private. I think it is the sort of thing you might see at funerals in European countries, but not in Britain.”
At George VI’s funeral in 1952, the King’s coffin was lowered into the Vault but the proceedings were not televised so the working operation of the motor has not been broadcast before, Mr Little said.
Photographs of the occasion taken from a distance show the new Queen Elizabeth II stood in front of the space in the floor after the coffin had descended.
She sprinkled earth into the vault and was stood with the widowed Queen Mother, her sister Princess Margaret and the King’s sister Princess Mary.
Philip’s coffin will rest on a catafalque in the Quire and be draped with his personal standard, and decorated with a wreath of flowers and his Naval cap and sword.
The duke also personally selected the regalia – the medals and decorations conferred on him by the UK and Commonwealth countries – together with his Royal Air Force wings and Field Marshal’s baton, which will be pre-positioned on nine cushions on the altar in the chapel.
The Royal Vault at Windsor was created between 1804 and 1810 for George III, who died in 1820 and is one of three kings buried there.
Also interred in the vault are George IV and William IV.
Others buried there include George III’s wife Queen Charlotte and their daughter Princess Amelia, George IV’s daughter Princess Charlotte and Queen Victoria’s father the Duke of Kent.
Princess Margaret, who died in 2002, was cremated and her ashes were initially placed in the Royal Vault, before being moved to the George VI memorial chapel with her parents’ coffins when the Queen Mother died just weeks later.
It is not the duke’s final resting place.
When the Queen dies, he will be transferred to the church’s King George VI memorial chapel to lie alongside his devoted wife of 73 years.
The tiny chapel houses the remains of George VI, the Queen Mother and Princess Margaret.
George VI was interred into the Royal Vault first and moved to the memorial chapel annex when it was built 17 years later.