Problem (half) solved - it's sciarid fly larvae! Now I know what they are, time to sort them I guess!

Typical! The batteries have ran out on my camera, however I did just find this info that kinda suggests that it could be threadworm. Threadworm infection is caused by Strongyloides stercoralis, a roundworm that lives in soil and can survive there for several generations. Mature threadworms may grow ...

Thank you for the replies.
It's definitely not earthworms, although I do have thousands of those too. So yeah I'll see if I can get a picture of them on here.

(I always thought you could catch threadworm from soil...silly wives tales)

Zoe

Hi, does anyone know how to identify the difference between threadworm and some of the other similar types of 'worm'. Basically I'm very new to gardening and am horrified to find my soil swarming with what looks identical to the threadworm my children had not so long back. Perhaps this is where they...