Career
In the first of two consecutive Summer Olympics in which he appeared, Astbury swam for Great Britain at the 1980 Summer Olympics in Moscow. In individual competition, he also competed in the preliminary heats of the 400 and 1500-metre freestyle events. At the 1984 Summer Olympics in Los Angeles, California, he claimed the bronze medal in the 4×200-metre freestyle relay, together with British teammates Neil Cochran, Paul Easter and Paul Howe, finishing behind the Americans and West Germans.
He also advanced to the B Final of the 400-metre freestyle, finishing sixth in the consolation final (14th overall), and competed in the preliminary heats of the 1500-metre freestyle.