Apologies for not getting back to you sooner.
I’ve had a prolonged go with water and soft microfibre cloth but it’s not budging which leads me to think it’s more likely an oil-based paint. We have a close friend who does modelling (no not that type of modelling! 🙄) and he has all sorts of equipment to polish and buff things so I think I’ll see if I can persuade him to have a gentle go with it.
Thanks again for all your input. 👍🥰