I found a dead one in my conservatory this morning which gave me the opportunity to have a good look! Don't think I would have been so brave if it had still been alive! Anyway, the posh name I've found is Pimpla Hypochondriaca. It is associated with the bee/wasp family & is parasitic in that they lay their eggs in caterpillars. I haven't found out whether or not they sting, though. Hope this helps :-)
