You're right zoony, most was channelled back to central government.
For a very long time time there have been geographical differences in supply and demand. Some northern local authorities were advertising houses to people in the south by the 1990s, and some people relocated in order to get housing. Like many housing staff, I thought RTB would be withdrawn once Labour were in government in 1997, but no. Its still too much of a vote catcher! With the social housing crisis we have now, it should be suspended. Scotland and Wales have both taken that step, England should follow IMO. Of course the best houses on the most desirable estates have nearly all gone into private ownership, reducing options for anyone now in need of housing. I don't blame anyone for taking opportunities that are offered, but it was a very uneven playing field.
The shortage of council housing is not only due to tenants buying their homes, but there was also a fair bit of demolition going on around the turn of this century. Many highrises, houses of non standard construction, and other less popular properties were knocked down.
Because we moved away from our home town in 1970, when I went to the council in our new area I was told we had no chance, as newcomers to the area. Housing need had no relevance back then, but family and council connections did. So we had no choice but to buy privately, which was a stretch for some years. However, that gave us the choice to live where we chose, and although we are no longer in the best house we owned we are at least mortgage free in retirement.
The story of one estate:
https://municipaldreams.wordpress.com/2014/11/18/the-manor-estate-sheffield/