When you see one out in the day, they are usually very ill. The first couple of times I saw this, near my previous house, where they are common (I had them breeding under the shed one year), they were clearly beyond saving. But I saw one recently - which was interestingly the first time I have seen a hedgehog in the vicinity of my present house (too many badgers round here) - it scarpered, which suggests it had rather more life left in it than the previous times. Though I wouldn't fancy its chances against the badgers...