During the early 20th century it became increasingly common to bury cremated remains rather than coffins in the abbey. In 1905 the actor Sir Henry Irving was cremated and his ashes buried in Westminster Abbey, thereby becoming the first person ever to be cremated prior to interment at the abbey. The majority of interments at the Abbey 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.

Answer this question, if possible (if impossible, reply "unanswerable"): What family has the Southumberland Vault?
unanswerable