Cutter worms

Cut worms work by completely curling around a stem. When they can touch head to toe (so to speak), they start chewing. If they can't curl around totally, they can't work, so something as simple as placing a thick stick, twig or such immediately beside (and touching) the stem, the cutworm can't do any damage. Some folk lengthwise split a bit of poly drinking straw and wrap that around the base of the stem. Whatever you use, it must be rigid enough to resist chewing jaws. 

Yes, they are widespread across the UK>

http://www.bbc.co.uk/gardening/advice/pests_and_diseases/nonflash_index.shtml?cutworms

According to the link, they should not be active for about another 4 weeks yet.

According to the link, they should not be active for about another 4 weeks yet.

Second generation larvae will over-winter in the soil, coming to the surface to feed when environmental conditions are favourable.

The overwintered ones obviously feel that conditions are now favourable  Twas this time of year that they ate my cukes

Charming little critturs aren't they 

The squashes that were attacked were poking through a ground sheet. Maybe that kept them warm enough to start munching. Anyway, I put my spares in today and wrapped silver foil around their bases.