I bought a 25ml pot of 258 broom yellow touch up paint by mistake, but after doing some research it looks like it is very similar to the correct yellow for my GP, which is 507.
The 258 is way off when I tested it on a stone chip on my GP, but I know that my paint has faded in some areas.

Has anyone got any advice for a better match. I'm not worried about the small stone chips. Its the peeling paint patches on the roof that I want to treat.

Plus, I have the 258 broom yellow to get rid of now, if anyone needs that code.
(three quid to cover the postage will do)
cheers.