"Overall, Brits viewed gambling as something of a sin"
Funny I've never thought of it as such. I have however thought of going in to a Bookies as being a highly unappealing trip due to the smell, decor, and rather unfriendly looking people in there. But with no smoking, and many Bookies sprucing themselves up they offer more of a middle of the road appeal. (Tbh I've placed one bet and that was as a nice little gesture for the wife. - I bet on Argentina winning the last World Cup.....the wife is Argentinian.)
Casino's however are the more refined, more polite side of gambling, (as many people see it.) But the whole process of having to sign up, come with 10 billion pieces of information to prove who you are, and the higher stakes tend to put people off.