 The club was the first in southern England to turn professional , making payments to players as early as 1890 and turning fully professional a year later . It joined the Football League before the 1897 – 98 season , left in 1900 because of financial problems , and rejoined in 1920 . Luton reached the First Division in 1955 – 56 and contested a major final for the first time when playing Nottingham Forest in the 1959 FA Cup Final . The team was then relegated from the top division in 1959 – 60 , and demoted twice more in the following five years , playing in the Fourth Division from the 1965 – 66 season . However , it was promoted back to the top level by 1974 – 75 . 
