After he was demobbed he undertook articles with
Peat Marwick Mitchell. He had been impressed by Hong Kong during his brief army service there and was delighted when he was sent by Peat Marwick back to the territory in 1950 to join its branch there. He became a senior partner in 1968 and retired from the company, now called KPMG, in 1978. During those ten years he served on a number of government committees, mostly concerning business practice and ethics. In 1973, he began founding the Hong Kong Society of Accountants (HKSA) to counter the severe shortage of accountants. He introduced the territory's own system of certification so that local people could become chartered accountants. Prior to this only chartered accountants from the United Kingdom and Australia worked in accountancy in Hong Kong. He was the first president of the HKSA, which started with a membership of 566, and is now known as the Hong Kong Institute of Certified Public Accountants, boasting more than 25,000 members. After his retirement in 1978, Macwhinnie, who had been a member of the
Royal Hong Kong Jockey Club since he arrived in the territory and was elected a steward in 1974, became chairman, serving from 1989 to 1991. == Death ==