Born in Scotland, the son of a Canadian-born Presbyterian minister, Greenfield moved with his family to Southern Rhodesia in 1909.
Returning to Rhodesia, Greenfield was called to the bar and began private practice as a barrister in Bulawayo.
In the first round, he and Garfield Todd tied, and Humphrey Gibbs gave his casting vote to Greenfield, who showed reluctance to accept the decision.
In 1968, he became a judge on the Appellate Division of the High Court of Rhodesia, in succession to Sir John Fieldsend.
[1] Ian Smith described him as "having a good reputation practising as an advocate at our bar, and as a cabinet minister his performance was immaculate", but claimed that "he was such a quiet, retiring person that he never came up for consideration as a leader" when Higgins retired as federal prime minister.