the early 20th century, for reasons of space, it became increasingly common to bury cremated remains rather than coffins. In 1905, the actor Sir Henry Irving was cremated and his ashes buried in the abbey, thereby becoming the first person ever to be cremated prior to interment. This marked a milestone as after the death of Sir Joseph Dalton Hooker in December 1911, the Dean and Chapter of Westminster Abbey chose to offer Hooker a grave near Charles Darwin's in the nave, but also insisted that he be cremated before. His widow however declined and so Hooker's body was buried in the churchyard of St Anne's Church, Kew. The majority of interments are of cremated remains, but some burials still take place – Frances Challen, wife of the Rev. Sebastian Charles, Canon of Westminster, was buried alongside her husband in the south choir aisle in 2014. Members of the Percy family have a family vault, "The Northumberland Vault", in St Nicholas's Chapel, within the abbey. The ashes of physicist Stephen Hawking were interred in the Abbey on 15 June 2018, near the grave of Sir Isaac Newton. The memorial stone, bearing the inscription 'Here lies what was mortal of Stephen Hawking 1942–2018', includes a form of the Bekenstein–Hawking entropy equation relating to black holes. In the floor just inside the great west door, in the centre of the nave, is the tomb of The Unknown Warrior, an unidentified British soldier killed on a European battlefield during the First World War. He was buried in the abbey on 11 November 1920. There are many graves in the floors, but this is the only grave on which it is forbidden to walk. Burials See also: :Category:Burials at Westminster Abbey British monarchs and consorts The following English, Scottish and British monarchs and consorts are buried in the abbey: Edward the Confessor, King of England, in 1066 Edith of Wessex, Queen consort of England; wife of Edward the Confessor Henry III, King of England Eleanor of Castile, Queen consort of England, in 1290 (viscera at Lincoln Cathedral and heart at Blackfriars, London); wife of Edward I Edward I, King of England, in 1307 Philippa of Hainault, Queen consort of England, in 1370; wife of Edward III Edward III, King of England, in 1377 Anne of Bohemia, Queen consort of England, in 1394; wife of Richard II Richard II, King of England, in 1413 (reburial