What’s the symbol painted on the wishing well in red?
The number 9?
Just after the first pub scene, when Nick Frost reverses his car into the wishing well whilst pissed.

Can’t remember and can’t check ‘coz my DVD’s are all in storage.

And what relevance does it have to the rest of the film?

I know it’s full of old movie references and in jokes, but I’ve no idea about this one.

Yes it was a red number 9.

Not mentioned again in the whole film and not explained or referenced.

Ta Neal!

Must mean something to someone, but God knows what.