Thompson was born in Manly and attended Christian Brothers College there before studying at Harvard as a Churchill Fellow.
Afterwards Thompson served in the RAAF from 1942 to 1946 as a pilot in the 460 Squadron, and on his return became involved in trade unionism.
[1] Thompson had joined the Labor Party in 1947 as a member of the Bellingen branch.
He held various positions (including president, vice-president and secretary) in the Padstow, Belfield, Campsie and Bellingen branches, and was an executive member of the New South Wales branch from 1969 to 1970.
He was elected to the New South Wales Legislative Council in 1974, serving until his retirement in 1988.