Who is stealing the hedgehogs' milk?

Someone or something has been stealing the milk from the hedgehogs' saucers!! As I was going into my garden today I noticed that the saucers were empty but  my hedgehogs were hungry and waiting for their milk but I had already  given them some milk earlier this morning. Who could it be? I could see no evidence of any strangers in my garden, no strange footprints or tracks  in the mud, nothing out of the ordinary at all. So what was I to do. I had a good idea, I would ask Pearl as she is very wise and always helps me out when I do not know what to do. Pearl advised me to put out some more milk and hide behind a bush to see who comes to drink it. So, I did just that. I put out 2 saucers of milk just as I usually would for my hedgehogs and I hid behind a bushy blackberry bush and I tried to keep very still and quiet. I waited and I waited and I waited, I was just beginning to get tired of waiting when I heard some rustling leaves over by my garden fence. I looked over and guess what I saw. There, with a whole parade of cats following behind him, was the naughty cat from the farm at the end of Wiggleway lane. He had come back again to my garden and this time he had brought all of his friends with him. Oh my goodness, so many cats.  So many cats drinking the hedgehogs' milk. I saw that the hedgehogs were also watching and were afraid, they had curled up into little balls to protect themselves.
Now I have a problem, how do I stop the cats coming to drink the hedgehogs' milk ? There are so many of them, a whole gang ! I will ask  Pearl again, she will know what to do .