"It's good news for everybody except housing developers, or the rich with "buy to let" portfolios which would then devalue somewhat."
It would have to be social housing to be effective - like the postwar housing developments. Apart from some "flat in the sky" projects many of those developments were solid and neighbourly - even if on the edge of town.
A recent survey of new housing showed that a large amount was being bought by overseas investors - especially with the drop in value of Sterling. They weren't necessarily even renting it out - just a safe place to keep their money. Can't remember the source - but the calculations were that no matter how many new houses were built for sale - they wouldn't change the un-affordability for most people in this country.