RAT Zapper 2000*, Chocolate Digestive, Done!
That is what I refer to it as. Got it for £20 off of the Rain Forrest lot, worked when we had rat problems last year and chalked up about 4 kills.
It zaps and kills them instantly and you just remove the containment pen and pour it into a bag and bin it. Sometimes they get a bit stuck to the bottom and you need to pry them off.
Having said all that, I ended up getting a pest controller in from Trust-a-Trader because they kept on appearing. Over three visits, he laid poison, identified how they were getting into the house and when they were appearing no more, blocked the ingress point.
Think the whole lot cost £125.