Ravenous, relentless pest

This pest has done its best to destroy near enough everything this year. Lettuce, squash, courgette, leeks, onions, cucumbers, parsnips, carrots and brassicas.
Starting to gain a bit of control now, but what exactly is it?
Sorry bout the duff photo.

Totty

Where are you finding it? In the soil? Or on the plants?

Are you guys sure it is a cutworm.  It looks very much like the larvae on my parsnips. These are on the leaves and turning them brown where they are being eaten. I thought they were sawfly. Are they similar looking?
Also I read that cutworm is mainly in the soil. Is that right?

Not easy to judge the scale from Totty's photo - if it's less than 1cm long it does look similar to the "saw-fly" caterpillars infesting some grower's parsnips which has been mentioned in a few threads lately.

If it's actually the same size as in the pic (when you click on it) I'm leaving the country!   

They are found on plants, rolled up in foliage.