Andrew Boff is a member of the London Assembly.

Housing was understandably a big issue in last year’s elections for Mayor of London. As a candidate, Sadiq Khan called the election a “referendum on housing”. His eye-catching promises included the delivery of 80,000 homes a year and ensuring that 50 per cent of all new homes would be “genuinely affordable”. He would be the Mayor to get London building and solve its housing crisis. Or so he said.

Yet once safely in office, it has been astonishing to see the speed and shamelessness with which these promises have been dropped. First to go was the 80,000 homes promise. Now he denies even making it, despite it remaining (at the time of writing), clearly visible on his election website. Instead he refuses to provide any target for the number of new homes he wants to see built in London, to the exasperation of even his own party colleagues.

We might have to wait until the new London Plan is published in 2019, over three years into his term of office. In the meantime, London’s developers, boroughs, and housing associations – those charged with building London’s much-needed new homes – will have no certainty on the number of homes they need to build.

The only actual figures we have had so far are from the Government, which has agreed to fund 90,000 affordable homes in London over six years – yet still nothing from the Mayor as to how he will make up the difference.

Meanwhile, his promise that 50 per cent of new homes should be “genuinely affordable” – certainly a foolish promise to make, but one that was made all the same – has now been watered down to 35 per cent. Not that we know what this 35 per cent is supposed to represent, or even what ‘genuinely affordable’ even means. By contrast, his predecessor Boris Johnson had a very clear target to build a record number of 100,000 affordable homes in his eight years as Mayor, and this is what he delivered.

When challenged on any of this, Mayor Khan falls back on a cynical and predictable attack on his predecessor’s record. His favourite line is to quote a highly misleading figure of 13 per cent – the number of affordable homes given planning permission in the last year of Boris’s term. This is meaningless because it ignores the number of homes that were actually built, of which 36 per cent were in fact affordable.

But the real problem here is Sadiq Khan’s obsession with percentages. He is less interested in how many new homes are actually delivered, as long as he can say that 35 per cent of them are “genuinely affordable”. Yet this offers little comfort to the next generation of Londoners, many of whom are struggling to reach the housing ladder, and urgently need to see an increase in housing supply. A young family, looking for a new home, cannot live in a percentage or an approval – they need a genuine, tangible home that has actually been built.

The only way to deal with London’s rising house prices and rents is to increase housing supply as much as possible, as fast as possible. Any sensible Mayor should recognise this. Yet far from the revolution in housing we were promised, Sadiq Khan’s tenure is shaping up to be a triumph of spin over substance.