We should have a test for every policy
1) does it restrict freedom?
2) If it does, is there a way to achieve the desired end using market forces (eg in this case a carbon tax or trading scheme – or reversing the ban on smoking…)
3) If not then is the resulting loss of freedom worth the benefits? (In this case I’d say no – patio heaters are not a major source of greenhouse gasses)

Unfortunately we have the ‘Al Gore made a film full of hyperbole, we must do something! Ooh, people like gas heaters on patios, but these people are generally nasty smokers who shouldn’t do that (because everyone should agree with my value judgments), so lets ban those, it makes me look like I’m ‘doing something’.