"Hedgehogs now appear to be declining in the UK at the same rate as tigers are globally – at around 5% a year, both in rural and urban habitats."
In the 1950s it was estimated there were 36.5 million hedgehogs in Britain
"Fewer than 1 million remain"
Be sure there is a 6 inch square hole in your fences, hedgehogs need to roam around. Buy or build them a house for winter.