He joined the firm of McLay, McAllister and McGibbon in 1922 and moved to Chalmers, Wade & Company in 1927.
In 1932 he joined British Insulated Cables at Liverpool, rising to be executive manager in 1942.
Following a post-war merger McFadzean became deputy chairman in 1947, and managing director from 1954 to 1961, of British Insulated Callender's Cables.
He became a friend of Harold Wilson in whose Huyton constituency the company was a major employer.
[4] A committed pro-European, he made only one speech in the House of Lords, during the debate on Britain's entry into the European Community on 26 July 1971.