Prince Philip will be moved upon the Queen's death; to be buried together in decades-old matching coffins

The small memorial chapel where the couple will permanently be laid to rest also has the coffins of the Queen's parents and sister.

Prince Philip will be interred in the Royal Vault of St. George's Chapel after his funeral on Saturday, but his coffin will be moved in the future to reunite him with Queen Elizabeth II, his wife of 73 years.

When the Queen passes, she and Prince Philip will be buried alongside each other in the King George VI Memorial Chapel, also located in St. George's Chapel. Until then, Prince Philip's coffin will be kept in the Royal Vault, which is itself the final resting place of many royal ancestors, including three former kings- George III, George VI, and William IV.

It is also where Prince Philip's mother, Princess Alice, was laid to rest following her funeral at St. George's in 1969, until she was moved to the Convent of St. Mary Magdalene in Gethsemane on the Mount of Olives in Jerusalem almost two decades later to fulfill her last wish, reports Royal Central.

The small memorial chapel where the monarch couple will be permanently laid to rest also has the coffins of the Queen's parents King George VI and Queen Elizabeth, The Queen Mother, as well as the ashes of her only sibling Princess Margaret.

The queen and the Duke of Edinburgh will also have matching coffins, whose construction circumstances including the year it was made remain a mystery. The coffin, made from English oak and lined with lead, was "inherited" by Leverton and Sons when they became the official Royal Funeral directors, reports Mail Online.

It is a tradition that members of the royal family are buried in lead-lined coffins, which helps preserve the body for almost a year as long as the coffin is airtight stopping any moisture from getting in. Princess Diana's coffin also weighed a quarter of a tonne due to the amount of lead lining.

Buckingham Palace had looked at a number of choices for the coffin, including a £900 casket made of wool, before they finalised upon the three-decade-old coffin for Prince Philip, reports The Sun.

The coffin of the royal who died on Friday at the age of 99 will be carried from Windsor Castle to the St. George's Chapel in an open-top electric Land Rover Defender 130 Gun Bus he helped create and modify.