How does right to buy work and why is Boris Johnson planning to extend it?

Even though it is more than 40 years old, the changes wrought by Margaret Thatcher’s right-to-buy policy can still be felt in Britain today. It established the story the Conservative party continues to tell about itself, of being crusaders for opportunity for all; it transformed the way people thought about what it meant to own or rent their homes; and it shifted almost 2m social housing dwellings into private hands. It became the emblematic policy idea of a prime minister who was pretty unpopular at the time, only to rule for another decade. No wonder Boris Johnson wants a piece of it.

No wonder, either, that he is not the first Conservative leader to propose extending right to buy to housing associations. But there are very good reasons it has not happened before.

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What is the government expected to propose today?

In his speech to backbenchers ahead of the no-confidence vote, Boris Johnson promised that if he won, he and the housing secretary, Michael Gove, would “be setting out plans to kindle that dream of home ownership in the hearts of millions who currently believe it is beyond their means.”

The proposed mechanism is to extend the right to buy to people living in properties owned by housing associations – not-for-profit bodies that rent low-cost homes to about 2.5 million people.

Crucially, housing associations are not state-owned. At the moment, people living in council properties can get a discount of up to 70% of the market value of their home, up to a maximum of £87,000, or £116,200 in London. There is a scheme in place for housing associations but it limits the discount to a maximum of £16,000.