Opium dens in London weren’t like that of San Francisco ( a friend wrote a couple of books on it - they were more like a back room in someone’s house in London.
There is the Dore engraving supposedly of London, but the pipe looks very wrong.
A great grandfather as a young man worked in Limehouse 19th C as a boat builder ( tall ships back then) and did smoke at Limehouse and said it was “ the closest thing to heaven”
He died long before I was born so couldn’t ask him about it, but it was part of family history ( he had a gambling habit too) so can’t have been much fun for his poor wife and 7 children when money was tight.
In U.K. Laudanum seemed to be the preferred way.
Bizzarely in U.K. law it’s still technically illegal to own an opium pipe and lamp and yen hok - no other paraphernalia is “illegal” here, just specifically Chinese opium smoking stuff.
( Roots in a century old racism?)