Did some research - definitely "pea and bean weevils" - the damage looks exactly right. The little scallops out of the edges of the leaves are a perfect match. Unfortunately, they are easier to prevent than to eradicate. Fleece over the beans as soon as you plant them will do the trick as it stops the adults from arriving, and hoeing around the plants will disrupt the lifecycle. It looks like hoeing to salvage as much as we can and using fleece to protect later beans that we plant out. Older plants don't suffer as much damage, but young plants can sometimes be killed by them.
Looking around the other plots, I'd say that nearly everyone with beans has the problem to some degree.
Have other people here had problems with them?
What did you do and did it help?