They're definitely CORGI Registered - which makes you wonder how much faith you can have in self-regulation. I do have a detector - it's like a smoke alarm but it sits on a cupboard instead of hanging from the ceiling. And they gave me a gas safety certificate before they left - they do all the safety checks for my landlord's letting agent.
My thinking is that I have insurance so, providing I'm not in the house, the thing can fall off the wall and the gas explosion can level the entire terrace - nothing to do with me at all