Originally Posted by Pudding4brains
Judging from the amount of (pro)legs or whatever they're supposed to be called it's not a 'caterpillar' but a sawfly larva, so you'll probably need to looking at different references
Originally Posted by H Dogg
Its Athalia rosae the turnip sawfly.
Whoops.....well, when I said 'caterpillar'....... I actually meant sawfly!!.......just a slip of the finger you understand!!
And that does explain why I couldn't find it on any of my searches .
I understand that they are a bit of a pest and unfortunately I found it up our allotment.
However I did only ever see the one, so not a lot of damage was done this time.
Anyway, thanks for the help and ID Arp and H Dogg.
I shall definately be on the look out for the legs next time, so at least I have learnt something today!