I'm currently restoring a Hercus 9". Regarding the colour, I think the shade actually changed somewhat during the years as I've seen various shades on different components, notwithstanding the fact the paint looked original in each case. Nevertheless I believe it was produced by a company called Crowhurst Paints, now part of Solver(?). The shade is "Hercus Green" which I guess really doesn't help one iota!
A lot of the machines out there are department of education school lathes, and they are a beige. Mine is ex school and I'm not sure if that beige job was actually repainted ex factory on assembly, as it was stripped right down during the repaint, and I doubt anyone else would go to that trouble. My guess would be they painted then machined the castings and had different parts piled up ready to build lathes, if it was a dept of Ed order they'd repaint those parts beige, while other parts not requiring machining were painted beige straight from the get-go. That's just a guess BTW based on what I'm seeing as I'm stripping and rebuilding as every part is going back to bare metal.
If you're looking to match the colour try to find an area where the paint is original and in good condition. Take the piece of and go to a good auto paint supplier and they will be able to match it. What led you to believe it's had a paint job BTW? It looks original from the photos, including the Hercus sticker on the HS. Looks like a good little lathe
Pete