Now this is an identification challenge. Its a female crane fly, and I think the green eyes means its one of the Tipula Lunatipula subgenus.
The common one seems to be vernalis but there is no dark stripe along its back or dark triangle and that is a spring crane fly. Having wasted half a day digging around on the internet I tried the Natural History Museum ID forums. No one has come up with a better suggestion and it seems the stripes are often less prominent so maybe it is just a vernalis up way past its bed time?