Macdonald had a conservative philosophy. He was a member of the United Australia Party (UAP) for many years but had become distressed by the links between big business and the party.[2] He entered parliament as the Independent UAP member for Mosman after winning the seat at the 1941 state election. Macdonald defeated the sitting UAP member, General Herbert Lloyd,[3] in a campaign marked by bitter attacks against Lloyd who had accepted a position as Director-General of Recruiting without resigning from parliament.[4]
In parliament, Macdonald campaigned for the state government to take a loan of £5,000,000 to revamp the public school system. He also called for education reforms including daily prayers and a ban on caning.[5] In 1943 he led an attack in Parliament on the atheist Sydney University Professor of Philosophy, John Anderson, who had said there was no place for religion in education; both houses of Parliament condemned Anderson but the university's senate backed him.[6]
Macdonald did not join the newly formed Democratic Party or Liberal Party, but easily retained the seat at the 1944 state election.[7] In that year he co-founded the Political Reform League with another independent James Shand, the member for Ryde. This was intended to be the basis of a new centrist party in the state but failed to attract public support. Macdonald was defeated by the official Liberal Party candidate, Pat Morton, at the next election in 1947.[8] He then retired from public life. He did not hold parliamentary or ministerial office,[1] but was said to be only the second active ordained Christian minister in the Legislative Assembly since the Reverend J. D. Lang.