His mother, Elizabeth, (Lady Betty Wilson CBE), was a granddaughter of Sir John Langdon Bonython, owner of The Advertiser and a member of the first federal House of Representatives, and a great-granddaughter of Sir John Cox Bray, South Australia's first native-born premier.

In 1966, Wilson was elected to the House of Representatives for the Adelaide seat of Sturt, which his father had held with one break since 1949.

It was considered a fairly safe Liberal seat, but at the 1969 election there was a strong swing to Labor in South Australia, and Wilson was unexpectedly defeated by Norm Foster.

When the Liberals came to power under Malcolm Fraser in 1975, he was initially passed over for ministerial preferment in favour of the more conservative John McLeay Jr.

In 1981, McLeay was dropped from cabinet and Wilson was appointed Minister for Home Affairs and the Environment.