And councils have finite budgets so every £ extra spent paying someone's rent is a £ that isn't spent on supporting and caring for the elderly and the disabled and the mentally ill / funding schools / running buses / maintaining cycle paths and parks and play areas and libraries.

Unfortunately there are a number of disadvantages to this:

1. Making affordable housing a condition of planning permission doesn't cost the council anything, whereas houses built in other councils' areas would have to be paid for.

2. The vast majority of social housing users have jobs and loved ones. If someone has to buy a car to get to work, or can no longer get babysitting from their parents while they work, or moves somewhere with lower wages, such a move makes them poorer.

3. Many of the jobs these people are doing need doing anyway, so they'll have to be replaced - possibly with someone with a longer/more expensive commute. Some people have a certain cynicism about capitalism, and are sceptical as to whether these jobs' wages will rise at all, let alone rise enough to cover a more expensive commute.

4. Regeneration often involves demolishing homes poor people live in. As some minorities are richer than others, regeneration that sends poor people out of a city is also regeneration that sends certain minorities out of the city. Some people feel this has shades of "ethnic cleansing".

Citation needed. Also If I buy a flat and I have to live with problematic people, how does that benefit me?

We’re talking about the most desirable areas in the world here, trying to force in social housing is just weird.

It’s not like there isn’t a bunch of places within a very reasonable commute where they could put social housing. Fuck, I used to commute from Reading for a while!