“Her appearance at the Abbey in a family fringe tiara echoed the bridal attire of her first cousin, Queen Elizabeth II, in 1947.”

The jewel has much royal significance and was first worn by Princess Marina.

In 2019, Lady Gabriella Windsor also sported the diadem when she married Thomas Kingston.

It could hold a valuation of up to £3million, according to Ailsa Russell, a gemmologist and appraiser from Prestige Pawnbrokers of Channel 4’s Posh Pawn.