Thanks Ian. I thought your suggestion could be a possibility but then I had a look at another shot I'd taken and it appears there are similar things on the other fore foot, though this doesn't rule out your idea.
The badgers arrived a few years ago and they (or perhaps their offspring) have been visiting regularly ever since. While I can prepare for getting some photos there is a lot of luck involved. Apart from the animals not arriving, the slightest sound, particularly with the badgers, scares them off.
It's probably just the fleshy web between the toes, remember these animals dig with their forefeet and as they dig they spread their claws, it may help to gather more earth if the web helps them, Badgers have 5 toes, foxes and dogs have 4 toes Duncan