Parasitoid wasp

I think I've happened across another variety. Those little three nobbles on the top of its head look wasp-like anyway.  It was tiny and I nearly didn't give it a second look.

It may be an ichneumonid but that's as far as my ability can get - it's got a little pale patch underneath that I can't seem to ID despite finding this great little guide.  I've read some parasitoid wasps grab prey, bury it in a hole, lay their eggs on top and seal the hole with mud - gruesome!  This one looks to have found an unsuspecting host in the depths of this thistle flower to lay its eggs on.

If only our school careers advisor had told me there was more to jobs than banks, accountancy and libraries!