They're like little drops of something. I'm thinking pollen/nectar, but some of it refuses to shift with some vigorous rubbing. Are there any cleaning products that are same for forks and might shift it?

Wurth Industry cleaner is good for that sort of thing, but not sure if it'll affect seals etc. Should be ok if you clean it off. Good for all sorts of sticky residues.

soap?

Had a little go with a cloth and some Fairy, but, like an idiot, the cloth made it all linty so now the spots are a bit fluffy 😳 Bought some lint free stuff so I'll have another go tomorrow. I'm just a bit scared of them going past the seals but most of them are pretty high on the stanchion.

My other half reckons it's caterpillar poo/pee. There are a lot around here at the mo', and there does seem to be a bit of 'drizzle' when you go under a tree sometimes 🙂

T cut.

Could be tree sap, remove with very hot water.