According to Cossey: ‘Tigers’, 74 Squadron frequently had detachments at Rochford between October 1939 and June 1940. However, my notes from Ernie Mayne’s logbook show that ‘B’ Flight were at Rochford on both 6 and 20th September, 1939, when they carried out flying for the film: ‘The Lion Has Wings’. My notes on Marmaduke Ridley, 616 Squadron, show that 616 were at Rochford from May 26 to June 6, covering the Dunkirk evacuation.
Hope this is of help.

Best Wishes.
Robert.