Hi veefrommk
How lovely that you had a hedgehog in your backyard. I guess if he wasn’t used to seeing you he would be a bit scared, but hopefully he will remember that there was a water source there. If you leave water out daily for him he might be back when he thinks you aren’t looking! It seems strange that there are wild animals living in a City, but so there are and it’s one of the charms of hedgehogs that they are wild and yet are still prepared to let their lives overlap with us humans.
But yes, you were probably right that he was off to another house – or at least garden. Hedgehogs need several gardens to make up a large enough area of habitat for them. You may be lucky enough that he includes your backyard in his regular route if you make it worth his while by offering regular water and maybe a bit of cat food.
Good luck. Hope you see him again. Let us know if you do.