Another Dave wrote:
It's always worthwhile using a search engine to find what you want. I
found some paint of exactly the right kind and colour from this lot:

https://www.brooklyntrading.co.uk

That's a bit niche. Their entire stock:

Ronseal Radiator Paint - Smooth Gloss 1Coat - Magnolia - 750ml
Crown Solo One Coat Satin Paint - Wood & Metal - Purple Heart - 750ml
Graham & Brown Matt Emulsion Interior Paint -Village Green - 2.5L
Craig & Rose Interior Wood Paint - Acrylic Eggshell - Terracotta 750ml
Craig & Rose Wood Furniture Paint Acrylic Eggshell - Etruscan Red
Crown Breatheasy Wall & Ceiling 2.5L Taupe

Not bad if you want to paint some traffic lights, but otherwise...

As others have said ebay is worth a shot. Yesterday I ordered some
paint, again of the right kind and colour, from an ebay trader. It's
already on a lorry and should be here tomorrow.

I found loads of people selling half an opened tin, which actually would
have been fine for my application but for the 'collection only'.
And then there's people selling half litre tins for thirty five quid...

Theo