The descendants of the Russian imperial family have called on the church to give them “closure”, allowing the bodies of two missing Romanov children to be laid to rest with their parents on the centenary of their murder.

Princess Olga, the great-niece of Tsar Nicholas II and president of the Romanov Family Association, said the burial of the brother and sister, along with their three siblings and parents, would finally allow their family to “rest in peace” together.

The Princess, who lives in 13th century mansion Provender House in Kent, travelled with a dozen family members to St Petersburg yesterday to mark the 100th anniversary of the execution of the Tsar, Tsarina, their children and acquaintances in the mystery which has absorbed the public for decades.

Prince Michael of Kent, a first cousin twice removed of Tsar Nicholas II who bears a striking resemblance to him, flew to St Petersburg for the memorial, along with his wife Princess Michael and several other members of the family now living in Britain and across Europe.

They arrived in Russian in the midst of the latest debate within the Russian Orthodox Church about the bones of their ancestors, found in two unmarked graves proven by extensive DNA testing to be accurate.