I am generally pretty rubbish at ID and get shot down in flames, so don't hold your breath.
I wondered if this could possibly be Brachycyrtus ??
Take a look at page 9 of the attached link (which I hope works) and see what you think.
Lovely photo any way and almost certainly not a true wasp.
Your link doesn't work. This one does, I hope: http://www.brc.ac.uk/downloads/ichneumonidae_subfamily_key.pdf.
When it comes to what it is - I won't even guess. So, this time you'll get shot down in solitude (you have my sympathy in advance though).
This is a lovelyichneumonid! It's Listrodromus nycthemerus (Ichneumonidae: Ichneumoninae), a specialised parasitoid of caterpillars of the Holly Blue butterfly. Although sometimes very common (the ichneumonid seems to be the cause of the dramatic population cycles of the host butterfly), the adults are rather rarely collected. They oviposit into late instar caterpillars and emerge from the pupae. Within ichneumonines, the wasp is fairly distinctive in its colour pattern and the shape of the face (smoothly curved). The abdomen is rather short and markedly petiolate. Perkins covered this species and other ichneumonines in two volumes of RES handbooks, way back in the '50s.