Thanks for the quick response!

Need to re-watch the film and see if I can catch any serial on L-ES/ES-L – that would pin it down. I did look at the Wikipedia list of OCUs and 229 OCU but I was working on the basis they were at an overseas station rather than in the UK. Maybe they were detached or just fanciful story telling on behalf of the film producers!

EDIT
Just had a quick search and found this info – http://www.rafweb.org/OCUs1.htm which places 229 at Chivenor in 1951 and confirms the codes as “ES/RS” at the time.

Yes, its 229 OCU.

What was the film? I used to own the cockpit from Vampire FB5 RS-P, VZ193 (now owned by Jon H) – It would be good to see its fellow squadron members.