Thelwall, Cheshire born outside left Reginald “Bert” Watson started his football career with junior clubs Grappenhall in 1919, Fairfield United the same year and Monks Hall in 1920 before joining Witton Albion later the same year after an unsuccessful trial at Manchester United. He joined First Division club Oldham Athletic in December 1921 and immediately made his Football League debut at Birmingham, establishing himself as a fixture in the first eleven. Although they were relegated in 1923 Watson continued at The Latics, scoring 72 goals in 242 games over eight seasons before eventually leaving to join Southampton in June 1929 in a deal for the transfer of Billy Murphy. In November 1925, he scored twice in an FA Cup First Round match against Lytham; the final score was 10-1 to Oldham with the other goals coming from Horace Barnes (three), Arthur Ormston (two), Albert Pynegar (two) and Jimmy Naylor; this remains Oldham’s largest victory in the FA Cup. Watson followed this up with four goals in the next round, in a 6-4 victory at Stockton.
At Southampton Watson struggled to acclimatise to life on the south coast, despite being noted as a “great trier”. He made his debut for The Saints playing at outside left in the opening match of the 1929-30 season, a 3-1 defeat at Barnsley. Watson retained his place for the next five matches, scoring three goals, including a brace against Blackpool before losing his place to Stan Cribb. Watson was only third choice on the left behind Cribb and Johnny Arnold and was in and out of the side for the remainder of the season, making a total of 14 appearances in the Second Division, scoring four goals.
In the following season, he was only able to play when Arnold was playing cricket for Hampshire, and managed only a further five appearances, with one goal. Watson was more successful in the reserves, for whom he scored 36 goals in 63 matches.
In the summer of 1931, he was transfer-listed for a fee of £200 but was eventually allowed to return to Lancashire on a free transfer when he joined Rochdale in September 1931 after 5 goals in 19 appearances for The Saints. He only played for Rochdale for a few months, netting 8 goals in 18 appearances, before he retired in February 1932.