England was the final part of the United Kingdom to broadly prohibit smoking, with Wales and Northern Ireland instituting such a ban in April and Scotland last year. The Republic of Ireland made the move three years ago.
"Only by tackling the causes of illnesses will we be able to improve health inequalities and save lives," said newly appointed Health Secretary Alan Johnson. "A smoke-free country will improve the health of thousands of people, reduce the temptation to smoke and encourage smokers to quit."
International travelers were warned as their flights landed of the new rules in effect and of the $100 penalty for failing to obey. The message was repeated on trains, on posters and in TV ads.
The decision to ban smoking was widely supported, but has also elicited vociferous objections from many who say the government has gone too far.
Singer Joe Jackson, who moved back to Britain from New York after a clampdown on smoking there, has been a prominent opponent and has threatened to pack his bags again.
"You can make a self-righteous moral argument about someone inflicting something on you that you don't like," Jackson said. "I have things inflicted on me every day that I don't like. I happen to be allergic to dogs, I'm not screaming for a total dog ban."
But praise for the ban came from all corners, including the PDSA veterinary charity, which cited studies that cats and dogs could develop cancer from second-hand smoke and that hamsters and guinea pigs inhaling it could even suffer hair loss.
"The effects of passive smoking on humans are well documented, but pets are also affected by breathing in second hand cigarette smoke," said PDSA senior veterinary surgeon Elaine Pendlebury.