On 9 October 1911, he married Elizabeth Jane Black at Lanchester; the couple emigrated to Queensland and arrived in Brisbane on the Orama on 31 March 1913.

[1] Miles was recruited to the Queensland Socialist League in 1918, and was a founding member of the Communist Party of Australia (CPA) in 1920.

In the late 1920s, having risen to prominence in the CPA, he and Lance Sharkey won control on a platform of strong opposition to the Australian Labor Party's "social fascist" policies.

Miles adopted the pseudonym "A. Mason" after the CPA was banned in 1940, and re-emerged after the party was rehabilitated by the Soviet Union's entry into the war, but he was overshadowed by Sharkey.

He was described by an ASIO officer in 1953 as the "Grand Old Man of Australian Communism", and remained firmly committed to the cause throughout the revelations concerning Stalinism in the early 1950s.