Wasp found trying to parasitise a caterpillar on nettles i think?
No interactions present.
The fly looks like an ichneumon - possibly Amblyteles armatorius. It is difficult to see body colouring from your photo. Not sure about the caterpillar.
The caterpillar is actually a Hoverfly larva (Syrphidae). But I don't know which. But Mr. Syrphus will know for sure.
A touching faith in my limited abilities, William! I don't do larvae. If Gavin Broad finds this one there might be a better ID of the wasp, though.
recording wildlife with The Recorder's Year on www.hbrg.org.uk/TRY.html.
this is a great shot!
Lat/Lng: 51.216653057964, -1.4640151259664
OS grid ref: SU375465