Hi Laurence and Penny
My feeling, Laurence, is that these surveys become more accurate if the information from more than one source is combined, as I think happened with The State of British Hedgehogs. As you suggest, hedgehogs are not the easiest to survey.
The problem with this survey, Penny, is that as it covers all mammals in the country, the amount of publicity hogs get as a result is more likely to be limited. The survey, in general, was mentioned on Springwatch although not hedgehogs in particular.
