 By 1971 he was the Senior Puisne judge and in 1977 was promoted to Chief Justice of Queensland, holding the position until his compulsory retirement at the age of 70 in 1982.He was made a Knight Bachelor on 15 June 1974 for distinguished service as a judge of the Queensland Supreme Court.Wanstall was a foundation member of the Queensland Cancer Fund and for over twenty years was the Chairman of the Board of Trustees.