 After World War II, the house remained in the possession of the 7th Marquess of Londonderry with the Royal Aero Club leasing most of Londonderry House, though the family retained twenty two rooms for their own use.Following the death of the 7th Marquess in 1949, his widow Edith continued in occupation by permission of the Trustees of her late husband's Will, until her death in 1959.The Londonderry age on Park Lane drew to a close after the death of Edith, Dowager Marchioness of Londonderry.