Hats off to Islington Council for standing firm by its policy that 35 per cent of homes in new developments should be for genuine social rent, with a further 15pc cheaper than market rates.

In the months and years to come it is vital the town hall sticks to this target when making decisions on planning applications – not just as plans are submitted for the Holloway Prison site, but also in respect of proposals for the Archway Campus, where currently only 40pc affordable housing is planned – 10pc shy of what the figure should be, though not a bad quantity compared with other developments springing up across the capital.

The recent court ruling in Islington’s favour that developers can’t simply overpay for land, then claim affordable housing is too costly to provide, will help.

But that ruling simply says developers must provide as many affordable homes as possible without trying to pull the wool over the council’s eyes – it stops extremely far short of enshrining any kind of figure in law.

And yet a blanket approach is what I believe is needed if developers are to contribute significantly to solving London’s housing crisis. If councils do not uniformly insist on 50pc – or if some accept that a developer should base calculations on a 20pc profit but others expect affordable housing to eat into that – there is a danger that builders will simply favour areas where development is more profitable. If, on the other hand, a London-wide plan can be established that 20pc profit is needlessly high and 50pc affordable should be the starting point for any plans rather than the cherry on top, I think we’d see developers getting in line. But at the moment, despite Islington’s good solo work, there’s little real incentive for developers to change the way they work.