I might have agreed many years ago Orca but these days even 2 minutes on your PC/Device will bring up WW2 RAF Ranks etc and images of genuine RAF personnel - which is why I say it is as easy to get most details correct as it is to get them wrong - sloppy/lazy preparation and 'research' - a little keyboard time which would have added perhaps a few hours onto the schedule would not have cost a penny
Another free technique would be to watch a couple of old films such as 'Appointment in London' or 'The way to the stars'.