The only geranium with disected petals like that would be one of the many varietes of Geranium x oxonianum.

Could it be 'Sherwood'?

Geranium oxonianum 'thurstonianum' (bet you're glad you asked, lol)

Not so sure...'Thurstonianum should be a lot darker than this pic (Reddish purple) with only five petals, just as possible this could be any self sown seedling from that hybrid species. lol

Thank you all, i've made a note of it now so when I forget it in 10 mins (bit of a mouthful) I will have a reference.
cheers

no, bluespruce, it comes in this pale colour too - seems thurstonianum doesn't have named colours for some not terribly useful reason. Best bought actually in flower, bloomin' annoying.

Really Bamboo, that's interesting. I used to grow this cultivar in my mad geranium collecting days lol, with others like 'Southcombe Double' and 'Southcombe Star' etc, and this plant is a carbon copy of the sort of seedling that used to crop up on a regular basis.