The UK seems more advanced than the US in some respects..."poverty porn"

[dipsydoodle]

20. Not sure about that aspect.

see most recent changes here :

The Right to Buy rules were changed in 2005. Five years' tenancy is now required for new tenants to qualify, and properties purchased after January 2005 can no longer immediately be placed on the open market should the owner decide to sell. Such owners must now approach their previous landlord (council or housing association) and offer them "first right of refusal". If the previous landlord is no longer in existence, for example in cases where the former landlord was a registered social landlord which has ceased business, then the property has to first be offered to the local housing authority.

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At the 2011 Conservative Party Conference, David Cameron proposed to increase Right to Buy discounts in order to revitalise the housing market and generate receipts which could be spent on new housing. Social housing professionals have expressed concerns over the proposal.[9]

As of 2 April 2012 the Right to Buy discount has been increased to a maximum of £75,000 or 60% of the house value (70% for a flat) depending on which is lower.

The aim of the scheme is, for every additional home sold, a new home will be built for affordable rent, which will maintain the level of affordable housing while also increasing the number of properties available for those on the waiting list. The five year tenancy criterion will remain, and should the property be sold within the first five years of the original sale, part or all of the discount will be required to be paid back.

http://en.wikipedia.org/wiki/Right_to_Buy

As you can see no reference is made to market rates whatever for buy backs by local councils.