London has its very posh West End, and up until a few decades ago its poor East End, where all of the" Gor Blimey mate", cockneys traditionally lived.
(Though its been gentrified in part now)
I was told that this came about in the 18 &19th cs when coal fires were the norm for heating and cooking, causing huge amounts of smoke and smog.
The London Fogs were notorious even during the mid 20th c, and actually were responsible for killing people, though the "Clean Air Act prohibiting open fires put a stop to that.
Due to the Earths rotation, the general trend in Englands weather is that it drifts mostly from West to East, so the posh areas as a rule had their air pollution drift downwind, with the unfortunates who lived the furthest East getting the whole lot.
Apparently this, West/East divide was replicated in many other English cities, for the same reason though I can’t vouch for this personally.