What's hiding behind the freezer?

When I opened the door to let the dogs out this morning, instead of racing down the garden with Jack, Magpie snuffled around the porch, excitedly telling me that something interesting was behind the freezer. To be honest, my heart sank, as I had visions of a repeat of the rat episode, but still, small son and I carefully moved all the welly boots, and gingerly moved the freezer. There, in the hole below the freezer, was this little fellow ( well, actually he seems pretty large for a hedgehog!). It's been a long time since I've seen a hedgehog round here, so we were thrilled!
After removing the dogs from the scene, small son and I got him out, while he made the strangest noises I have heard. First it sounded like air deflating from a balloon, every time I tried to clear the leaves and sticks away so that I could get hold of him, followed by a series of cat like hissing and spitting noises. We took him to the bottom of the garden and put him under the shed where it should be warm and dry for the winter.