In DD's close of about 70 houses, I would say that 60 - 70% are now privately owned. In my own village the council recently refurbished all the houses it still owned in a small system built estate, this included putting external insulation on the houses so that is very evident which are the council houses and even in this estate of inherently not very attractive houses 60 - 70% are now privately owned.
I am sure the numbers are much lower in very large inner city council estates, but outside London council houses, especially older ones built to Parker Morris standards, are very attractive buys. Council properties have always been valued at the market price and then discounted, yes, the discounts are not as generous as they were, but they were always based on market value.
Household size has fallen from 2.9 in 1991 to 2.4 in 2008. That is equivalent to an increase in households of 17%, which equates with a demand for another 3 million houses before we even consider the housing needs of immigrants.
While immigration is an added factor mass immigration is only one factor in the increase of job insecurity and low wages. Many of the immigrants coming in, especially from the EU are highly qualified and are working in the professions, doctors, nurses, business managers, IT specialists and especially in the STEM industries where the lack of interest of British students in studying engineering and science is causing real problems. Many of the jobs with zero hours contracts are in retail, especially supermarkets and the warehouses supplying them, as the recent problems with Sports Direct has shown and the majority of retail workers are British. Similarly, many companies (like Sports Direct) do not directly employ staff but use agency staff, who can be taken on/laid off without any employers rights. Where immigrants can be found in low wage jobs it is in the industries British people do not want to work in; harvesting work in agriculture and horticulture is one.
Our economy has expanded and the number of jobs in this country has expanded, Many studies have shown that immigrants, overall contribute far more to the British economy than they draw out. The billions of pounds they pay in taxation each year would not be being paid if they were primarily in low paid work.