Hi Mouthy,
Sorry to hear about your dirty rat.We had one once,only one, a few years ago and we tried a sonic sound vermin shifter it was expensive and didn't work and the canary died( maybe a coincidence) I went down to the kitchen one morning and it had ripped through a bag of garbage it looked like a fox had got in. It chewed half way through a wooden rolling pin, it chewed practically all the way through an electric cable, it was crafty though, it didn't chew enough to electrocute its self.It tried to chew its way up through a floor board while I was hitting it's whiskers with a hammer .It tried to chew it's way through the bottom of a closed door.I chased it from top to bottom.It used to go back to bed around eight in the morning because I could hear it creeping above in the loft space.It had no fear and oh boy was it fast!
In the end I got that mad I put poison down in the loft space, within one day it had stopped it.About a week later as I went out through the front door I noticed an appalling stench.I opened the meter cupboard and nearly choked it had gone and died under the loft insulation which I had put in thinking it was vermin proof.The rat ended up on a bonfire in the garden .
All we get now, and that is out in the garden, is an occasional frog and a hedgehog.Put plenty of poison down but take care if you have pets and good luck.