Ichneumon wasp (Rhyssa persuassoria) aka Sabre wasp

This incredible looking wasp is a real eye-opener given its size and the length of the sheath. It was spotted by my daughter while on the walk by the reservoir in Dartmoor. I was busy photographing the Leaf rolling Weevil. This Ichneumon wasp was on a log with three others and a male. This female is parasitic on Horntail wasps. She uses her ovipositor to place an egg next to the larvae. You can see it out of the sheath with the tail turned under digging into the wood.
Well spotted Lorraine.

Canon 1000D & Tamron 55-200 lens