Alston was handed his debut for the Australian national team by head coach Joe Vlasits on 19 July 1969 in a 1–0 friendly victory over Greece, who were undertaking a tour of Australia, at the Sydney Cricket Ground. Alston later commented that as soon as he began playing for Australia, he was "no longer English". He won two further caps in 1969, playing in two out of three matches of a tour of Rhodesia against the national side in November, before scoring his first international goal the following year in a friendly match against Greece.