Pre 1973 vehicles had silver or white letters/digits on black surrounds or stickers straight on the bodywork, effectively any colour background. However your car requires the now standard number plates using the correct size letters and reflective materials. It also has to show the British standard and the postcode of the plate manufacturer. So the precised answer to your question is you need conventional white and yellow plates. Why give the filth a reason to pull you over?
I did and would.
PS 77 on a Golf GTi in black and silver - "Oh my brother made them for my birthday and put them on a wheelbarrow. My initials and favourite number. I thought I'd put them on my car"
That was 1985 and he is the boss of a massive double glazing company so sort of speaks volumes.
Pre 1973 vehicles had silver or white letters/digits on black surrounds or stickers straight on the bodywork, effectively any colour background. However your car requires the now standard number plates using the correct size letters and reflective materials. It also has to show the British standard and the postcode of the plate manufacturer. So the precised answer to your question is you need conventional white and yellow plates. Why give the filth a reason to pull you over?