No interactions present.
I don't think this one's an aphid, I think it's one of the true bugs in Heteroptera-Hemiptera (aphids are related but fall into another part of the Heteroptera: Sternorrhyncha). Aphids are usually more globular, and if they have wings they are usually held away from the body, or pitched like a tent, rather that flat over the body as in your photo. Can't suggest a species I'm afraid, there are quite a few small green true bugs and I'm not very familiar with them.
Entomologist and biological recorder
Dear Martin, WOW! We were certain it was an Aphid[just shows were not very good with greenfly families!].
I had a quick browse through the galleries on the British Bugs website and have found a possible candidate for this one, which is Malacocoris chlorizans:#http://www.britishbugs.org.uk/heteroptera/Miridae/malacocoris_chlorizans.html
Can't be certain that it is what you've photographed, but it looks very similar.
Dear Martin, that does look extremely like our fuzzy photo but I've noticed one thing, our photo is shorter but rounder than the one on the website. Dad says it's my bedtime now, [poo!]
See what you mean, but it looks like your photo is taken at a slight angle, while the ones on the British Bugs website are from directly above, so that could explain the difference? It's a nice bug in any case!
Lat/Lng: 53.465066866632, -2.2487149536937
OS grid ref: SJ835965