It's got some value, LB, but it needs to be used with caution. It's unfortunate that the map might suggest that hedgehog communities are thriving around the country, when actually the opposite is true.
I've lived here thirty years. I used to hear hedgehogs rustling away in my garden, and in other people's gardens as I walked to the shops, every evening. I've had hedgehogs eating out of my cats bowls on my front doorstep, even at the same time that there's been a cat eating there too. Sadly though, I've not seen or heard a single hedgehog around here for over a decade :(