My apologies... I saw the "pub" and "smoking" bit, it seems it didn't fully sink in that the OP was asking about London pubs rather than UK pubs. Of course you don't get many rural pubs in London!

And I suspect my reply (about pavements) was based on my experience of walking along Bishopsgate one recent Friday night and finding the pavement crowded with people with a drink in one hand and a cigarette in the other. Probably typical of that part of London but not typical of other parts of London.