People have been pretty easily sucked in to following the Government's characterisation of the smoking ban as a ban on smoking in "public". It is the converse: one may smoke and resmoke along the Queen's highway, but not in a privately-owned restaurant.
One may smoke in a privately-owned home, indeed, one may smoke in a publicly-owned home, and many are known to do so. One may not smoke in a private members' club, despite such premises being legally very similar to privately-owned dwellings (non-commercial, not enterable by members of the public in general). The reason is that private members' clubs employee people, who could suffer from passive smoking, and the law turns on whether people are employed on the premises.
I used to think that the justification for this was that some people are thought to have no choice but to work in smoky premises (I used to live in a village west of Cambridge where the only place serving alcohol, being the only employer other than the Post Office and a pig farm, was a private members' club). I'd thought this was some extension of the fallacy that since most people have no choice but to work, they have no choice but to work for a particular employer and cannot switch jobs. I now think it's probably just that the Government wants more precedents for measures which prevent people from engaging in risky behaviour through their choice of employer.
It's not clear how the home itself can ultimately be protected from these laws: I was working at home today, and had to put up with smoke coming in from builders next door. I should get together with my landlady and form a private members' club.
There are preposterous libertarian arguments in favour of smoking cigarettes near other people, grounded in the respect we ought to have for personal autonomy. We can just ignore these as nicotine addicts are not autonomous individuals, but even if we take them seriously, we are faced with massive market failure: I have been asked "do you mind if I smoke" with oftenness and politeness. Never however have I been offered any consideration. If the passive smoking externality could be eliminated by market mechanisms, I can scarcely imagine that even our old friends and colleagues at the Pinochet Institute for the Reduction of Poverty would not like to see the homeless and other vulnerable souls becoming professional passive smokers when they could be doing something else with their time.
So, massive transaction costs (possibly alleviable by technology) inhibit the market in passive smoking easements. We also lack the technology to privatise the air. We are foredoomed to produce a socially non-optimal amount of tobacco smoke. The debate about the UK legislation was concentrated on the physical health effects of smoking, which is unfortunate as by far the most egregious externality is that smelling someone else's cigarette when you don't want to is bloody annoying. With not a little confidence may we adjudge the fragrance of cigar, pipe and apple tobacco much more agreeable than that of the Lucky Strike, though even the aromatic sublimity of a virgofemorally-rolled Monte Cristo is unwelcome to those ailed by asthma, sore throats, or jogging. It's just rude. "Hello, I cannot control my cigarette addiction, so must it discomfort you as well". If people want to annoy each other with fumes, they should buy some land big enough for fumes to dissipate before they annoy neighbours, and certainly keep their filth off the public highway.
This law encourages cigarette smoking in the privately-owned uncovered space outside pubs; there's no fresh air inside a pub, and so there is no fresh air to be enjoyed in parts of London where pubs and stuffy cafés constitute the sole places where one may sit down.
The whole thing should be reversed: ban tobacco smoking on public land, and on land where it is likely thither to diffuse. Permit it in private, regardless of whether the premises are open to the public, frequented by people in the course of their employment or residential. At the very least, recharacterise the law as a "non-residential private smoking ban".