Once again, I think this is Pimpla hypochondriaca, a common and garden Ichneumon wasp. I say common and garden because it is just that, but that doesn't do this insect justice does it? Photographed on the garden gate this afternoon.
It is a spectacular insect, and is about 2-2.5cm long, head to tail.
Click HERE for the original post on this wasp, on the 18th september 2007, and click on the photo above to enlarge it substantially.