THIS FEMALE Ichneumon wasp was climbing up the studio window so I caught her in a bug box, photographed then released her and drew from one of the photographs.
As you can see from the scale on the base of the bug box (left) she is about 1cm long with an ovipositor that’s as long again.
She seemed to be a wasp with a mission, busily pacing up the window, pausing only to bend the long ovipositor over for cleaning. I can’t remember now if she held it bent beneath her or over her back. I think the latter.
Just in case there’s anyone out there who can identify the species for me, I’ve included this close up of the wing, as I understand the wing venation is one of the keys to identity. I wasn’t able to take a decent side view.
The nearest I can see in the book is the Large Ichneumon Lampronata setosas but that is getting on for twice the size. This looks like a close relative. The Large Ichneumon uses its long ovipositor to drill into wood to lay its eggs on the larvae of the Goat Moth.
Update; Thank you to Graham for suggesting Rhyssa persuasoria as the species. This is sometimes known as the Giant Ichneumon but a female would normally be two to four times as long as the specimen I drew.