Adrian Thorne was born in Brighton on 2 August 1937. He was spotted by Brighton & Hove Albion as a 17-year-old playing for his school’s Old Boys’ team in the Sussex County League, and signed for the club in August 1954. Like many players in the 1950s, his career development was interrupted by the requirements of National Service, and he made his debut in the Third Division South on 18 January 1958, at the age of 20, scoring in a 2–0 defeat of Southend United.
Going into the final game of the season, at home to Watford, Albion needed a point to secure the Third Division South title and promotion to the Second Division for the first time in the club’s history. With Dave Sexton injured, Adrian was selected to make just his seventh League appearance: he scored five goals as Albion won 6–0. Despite scoring a goal every two games, and finishing the 1960–61 season as the club’s top scorer, with 14 goals in all competitions, he was never an undisputed member of the starting eleven, and towards the end of that season he asked for a transfer.
Adrian joined Second Division club Plymouth Argyle for an £8,000 fee, but made little impact. In two years, he played only 12 games, scoring twice, and moved on to Exeter City during the 1963–64 season. He became a regular in the Exeter team that gained promotion to the Third Division that season, and remained with the club for another year before signing for Second Division Leyton Orient on a free transfer in the summer of 1965. At Orient, Thorne was reunited with former Brighton teammate Dave Sexton, now managing the club. but he played only twice for them in the League.
Adrian played 84 matches for the Seagulls scoring 44 goals between 1954 and 1961.