Picked up yesterday whilst out for a jolly on the bike.
A well used WWII other ranks side cap for the RAF. With WD arrow mark, but no date, though it is the WWII pattern and has a Kings crown badge and buttons. It is probably a J. Collett made example from the size and shape of the makers stamp.
I have also shown it next to the officers version I own to show the different quality of fabric and the different badges.