This extraordinary creature is an ichneumon wasp. I found two of them in my moth trap the other morning. They are nocturnal wasps, and are readily attracted to light. This is a fairly large wasp at 20mm (3/4 inch), long, with a red or orange body, antennae and legs. It has a strongly arched abdomen, which makes it look quite a fearsome wasp even to me, and I was quite wary of it, even though I knew it did not contain a sting. The females have a long ovipositor for laying eggs, and she could jab you a little with it if you were brave enough to handle one, but generally they will not harm you, say, compared to a hornet or a common wasp which will sting you, of course. It can easily be confused with other similar species so care has to be taken in identification.
The adults fly August to September, and can be found almost anywhere, including woodland, farmland, parks and gardens. The larvae are parasites of Heart & Dart moth caterpillars (Agrotis exclamationis). Common and widespread throughout.
Thanks to Craig Slawson and Gavin Broad of the Staffordshire Ecological Record for confirming identification.
Rear garden, Staffordshire, England. August 2017.