By the end of the 1929–30 season, six of the original twelve teams remained, having played in every campaign since the competition began.

The league saw regular changes in members between 1921 and 1928 and saw 23 clubs taking part.

A normal single league practice resumed in 1946 with 14 clubs now playing.

Some long term clubs experienced harder times and dropped into Division Two.

A "Two Up Two Down" system of promotion and relegation was applied throughout the period but was occasionally affected by departures from the league itself.

In the past, Unijet, Rich City, Matthew Clark and Badger Ales sponsored the Sussex County Football League.

Lewes were the inaurgural final winners beating Littlehampton 5-0 at Newhaven on 6 May 1939.

The league operated two region divisions, East and West, with the winners of each playing in a play-off For the first post-War season, the league also operated two regional divisions, East and West, with the winners of each facing each other in a play-off.

A two-division format continued for over 30 years, the only deviation being in the 1962–63 season when the unusually harsh winter weather made the league impossible to finish.

1 The 2019–20 season was terminated on 26 March 2020 due to the coronavirus pandemic 2 The 2020-21 was curtailed on 24 February 2021 and a Supplementary Shield was arranged.