Having seen numerous applications to join the Athenian League rejected, the club changed tack in 1951 and successfully applied to become members of the Metropolitan League. This was a league that included the 'A' sides of top Football League clubs, the reserve sides of 'professional' non-league clubs and a few amateur teams. Despite some people insisting the Sussex club could not compete at such a level, Horsham answered their critics in the best possible way by winning the championship at the first attempt. However, over the years the league became stronger and stronger and eventually the amateur clubs struggled to make any impact at all. Having decided to quit the league in 1956-57, Horsham finished that season at the foot of the table. During this spell the Senior Cup was won for the fourth time in 1953-54 when Whitehawk & Manor Farm were beaten 1-0 at Brighton's Goldstone Ground and the RUR Cup was also won in 1952 and (for the last time) in 1957