Vortex, you are of my era (Swinderby '75). I concur with your memory. 1 x Blue/Gray for Best, 4 x Wedgewood for day to day.
Also the very dark blue workshirts (issued as a one-off) + 2 x Blue/Gray coveralls issued as 'workwear' for manky jobs. About '78ish?
As an aside, at Swinderby, I was duty 'gash shag' one day and detailed to 'hump and dump' in Clothing Stores. I was told to dispose of a large black poly sack. Having a peek inside, I discovered, all screwed up, 23 almost brand new Wedgewood blue shirts all my size. I disposed of them into my kitbag.
I never ran short of a clean shirt again.