Tompkins served as president of the Hamilton District Law Society and was a member of the New Zealand Law Society Council, 1940–42. He was elected a
Hamilton City councillor in 1955 and served until 1958. He was admitted to the Inner Bar as
Queen's Counsel on 13 May 1958. He was appointed a
Supreme Court judge on 2 August 1963, retiring in 1969. A prominent figure in Hamilton, Tompkins held a number of roles including: president of Birthright Hamilton, 1958–1961; founding trustee and president, in 1961–1962, of the Waikato Savings Bank; chairman of Bartholomew Timbers Ltd, 1938–1963; member of the Board of Governors of the
Waikato Diocesan School for Girls, 1934–1963; and president and life member of the Hamilton Golf Club. He also served as a judge of the
Court of Appeal of Fiji and chairman of the Legal Aid Authority. == Death and legacy ==