When Hedgehogs are released after being treated/cared for in rescues they are often released into gardens, these are gardens where wild hogs regularly visit at night for food put out by the householder, there is access in/out of the garden so hogs can come and go freely, the only time a Hedgehog is put into a totally escape proof,totally enclosed garden is if the hog is disabled in some way such as blind or has lost a leg and would not be able to manage well in the wild, if a hog is healthy and able to fend for itself in the wild then that is where it should be returned, it should be free to roam as it wishes, to put a healthy hog into an escape proof garden is illegal.They are not pets they are wild animals, you are not doing them any favours by imprisoning a healthy wild hog in an enclosed garden.