New Brompton joined the Southern League upon its creation in 1894, being placed in Division Two because it was one of the last clubs to be invited to join the league. Upon joining the league, New Brompton turned professional, with the players agreeing to be paid 12 shillings per match, and promptly won the Division Two championship in the 1894–95 season. With a record of one defeat and eleven victories from twelve matches, the team concluded the season with a "test match" against Swindon Town, who had finished bottom of Division One. As 5–1 winners, New Brompton gained promotion to Division One the following season. In 1896 the club appointed its first manager when William Ironside Groombridge, who had previously served as the club's financial secretary, took charge of team affairs. Groombridge served the club, as secretary and sometimes manager, until well after the First World War.