Prior to William Hague who was the last (British) Tory leader never to be Prime Minister?

Answer 1

Austen Chamberlain. However, Chamberlain was only the leader of the Conservatives in the Commons, not the national party leader (which was Bonar Law at the time), so Chamberlain and Hague were both Parliamenatary party leaders who never became Prime Minister. Hauge was the first leader of the national Conservative Party never to be PM.

Answer 2

Austen Chamberlain

Answer 3

Michael Howard