1888 Charles Alfred Worsley Anderson Pelharn 4th Earl of Yarborough of Brocklesby Park, Lincolnshire, became the last private owner of Conisbrough's ruined castle through his marriage in 1886 to Marcia, eldest daughter of Lord Conyers.
c.1946 Conisbrough Urban District Council acquired the castle for a nominal sum from Lady Yarborough. Since this time much effort and money has gone into the preservation of the keep and curtain walls and the layout of the inner bailey made more obvious by careful landscaping. The castle is now in the care of English Heritage whose representatives, The Ivanhoe Trust, manage it and a visitors' centre contains items of interest about the castle and locality. The Trust frequently organise events designed to attract the attention of the public to this splendid monument and it is hoped to roof and floor the keep. During the early 1940s the Duchess of Yarborough graciously gave permission for the l0th Doncaster, 2nd Conisbrough Scout Troop to hold a garden party in the inner ward. Over £20 was raised by charging one old penny admission and another at the various booths and sideshows.