Thanks Leslie. Looking through my books I'd hazard a guess and say that its Megalomma vesiculosum - unfortunately I can only find drawings and one photo on the web which is of a larger more straggly specimen. I've seen this creature before around Britain and Ireland but never got a good ID on it.
Loads of Fire Worms in the Canary Islands - I got a shot a couple of weeks ago showing a 'fluffed up' one - something had upset it (not me) which I'll try to post.




