Born in Belfast, Hall-Thompson was the son of Samuel Hall-Thompson, and grandson of Rt. Hon. Robert Thompson MP. He studied at Campbell College in Belfast and joined the Ulster Unionist Party (UUP) in 1938. He was commissioned into the 8th Anti-Aircraft Regiment, Royal Artillery in 1939 and served during World War II, reaching the rank of Captain. For ten years from 1946, he served in the Territorial Army, reaching the rank of Major.
Hall-Thompson was elected to the Parliament of Northern Ireland at the 1969 election, representing Belfast Clifton. He won as an independent Unionist, supporting Prime Minister of Northern Ireland Terence O'Neill. In September 1970, he rejoined the UUP.
Following the abolition of the Parliament, Hall-Thompson was elected to the 1973 Northern Ireland Assembly for Belfast North, representing the UUP. The following year, he became the leader of the Assembly and also the Executive's Chief Whip, before joining the Unionist Party of Northern Ireland. Under this new party designation, he was elected to the Northern Ireland Constitutional Convention of 1975.
- Northern Ireland Parliamentary Elections Results: Biographies
- "Dictionary of Ulster Biography", Ulster History Circle
|Parliament of Northern Ireland|
William James Morgan
|Member of Parliament for Belfast Clifton
1969 - 1972
Position prorogued 1972
Parliament abolished 1973