Well I sent the photo to a 'bug' site and received a reply about 10 minutes ago..
apparently it is fairly common ..but I'm surprised not to have seen one before that being the case..
here is the reply from Joe I received..
'
It's one of the ichneumons, in the subfamily Pimplinae... there are very many similar species, but Pimpla instigator is supposedly the most common. The 'sting' is actually an ovipositor, and is what the sting evolved from in social bees and waps; ichneumons are a related group, like the more primitive sawflies.
You probably noticed that our site is about bugs - the order Hemiptera. You want Hymenoptera for these things, so I'd suggest bwars.com if you want to take it any further. I'm starting to attempt identification of ichneumons and their thousands of little relatives as a sidelines, but they're incredibly difficult - it makes dissecting a 2-mm-long leafhopper seem a doddle.
Cheers, '