Richard
I’m not quite sure what there was in terms of a planning commission in those days. I would have thought quite unregulated. The industrial revolution bought about unprecedented levels of urbanisation in the UK. The rest of Europe did not catch up until the 1950’s. With it came vast wealth for some resulting in incredibly high levels of wealth equality.
The wealthy were always looking for passive income, so with urbanisation and high demand to feed the industrial growth, housing was a perfect vehicle. The speculative builders wanted a piece of this pie too, so were more than happy to jerry build high density housing for the less well off creating a cash cow for the investors.
Most investors had no idea who they were renting to either or were they involved or interested in any way as being social landlords.