I see that Vesternet says that a dimmer WOULD work in a UK house without a neutral wire at the switch. Although not as safe, why wouldn't a homeowner simply wire up such a dimmer circuit for their lights? This is assuming the bulbs are dimmable. I also assume it would mean you'd want to turn off the lighting ring main at the RCD before any serious work on the bulbs, as you might not be able to rely on full isolation at the light switch, although I guess removing the bulb would simply open the circuit, and the switch could perhaps fail open as a default/safety measure.