Well, there are smoke alarms in bedrooms. People have ways of getting around this, I think, but still no-one's going to thank you if you set it off and the whole house has to clear outside! (Though, honestly, it was usually people burning things in the kitchen that set them off in my experience.)
For some reason, I was looking at the accomdation brochure the other day, and I'm sure it said something about the smoking policy being under review, so I'm not quite sure what it will be next year.