Basically you are correct. The wartime red and blue were not however called 'Dull Ident Red' or anything like that - they were simply termed 'Red' and 'Blue' (and 'Yellow'). There are some documented instances of the pre-war bright red and blue shades being used (erroneously) in wartime, one that springs to mind is Gloster manufactured Hurricanes in 1940. The reason could be as simple as their having large stocks of the old paint.
And no (before anyone asks) - the wartime roundel colours do not appear in BS381C.