An ichneumon wasp checking out a caterpillar of the cinnabar moth, Tyria jacobaeae (Lepidoptera: Arctiidae), presumably as a potential host for an egg. This time the caterpillar was lucky and the wasp flew away after the caterpillar waved its head about a bit.
The wasp looks similar to this one I photographed a few days ago checking out a caterpillar of the moth Depressaria daucella. I suspect they both might be member of the Anomaloninae (Hymenoptera: Ichneumonidae). See here for further pictures of this group.
Photo taken in the field below Chazey Wood, near Caversham, UK, on 2011-007-02.