They topped about a quarter of the plants, taking the bean in most cases and discarding the stem, leaving a neat hole in the bed next to where the plant had stood.
And then I had a plan. Instead of tossing the Christmas tree on the bonfire - I don't have a shredder - I'd spread the prickly leaves around the broad beans to see if it would stop the critters.
A week on and nothing has been touched. Now I'm just waiting to see if the beans I've resown to replace the losses come through this prickly carpet.