Strange Little Biting Bug UK (Picture)

I come in from being outside in the back garden after messing around with an Alder tree (getting in between the leaves to water it in the pot), and can instantly feel something biting my arm! I look and there's this tiny little yellow bug biting me. It couldn't be anything else other than this bug, as it was in the exact location where the stinging (biting) was coming from. I blew it off my arm and managed to catch it. The bug looks like some kind of hybrid green fly. It's mostly yellow in colour, with a red stripe starting at the eyes and going down the side of the body. It also has white and red Antennae (feelers).  If you look carefully you can see that it does have a mouth needle for piercing through humans skin. Like it did to mine. Strange little bug.

I would post the original picture of it caught in a glass but the insect is so small in comparison that its not really worth uploading. But take a look at it magnified approximately 6 - 8 times above. Click the image to enlarge. Weird little insect. Does anyone know what this is? Can you identify it? The bite has not left me with any lasting effects, so I don't think its particularly dangerous. But I'd still like to know if this is just some well-known insect that I've never seen before, or something more exotic and not native to the UK.

Update: This insect has been identified as the nymph of a Campyloneura Virgula. Thanks goes out to the very knowledegable AmandaB over at the nhm.ac.uk natureplus forum for quickly resolving the mystery.