Today we report on parallel London-wide scandals: that of homes sitting empty across the capital, and that of the lack of adequate permanent social housing.

While one of these may not have directly caused the other, there can be few more fundamental contrasts between the haves and the have-nots: every empty home could potentially be occupied by someone in need, and for every family with two homes (and for many others besides) there is a family with none.

Both scandals have as their root cause the damaging attitude of recent decades - by politicians and by individuals - that homes are an investment opportunity rather than a human right.

Islington and Hackney are to be praised for their policy on limiting "buy to leave" sales, but in Islington's case the fact the number of empty homes has barely changed since it introduced penalties suggests more detection and enforcement are needed. Hackney's clampdown on overseas and buy-to-let sales, by contrast, has yielded some good figures for owner-occupiers in new builds.

Meanwhile Haringey's questionable data collection does little to aid the necessary London- and UK-wide understanding of the housing crisis.

I doubt additional council tax would be an adequate deterrent to anyone wealthy enough to own two homes. Instead, it should simply be illegal to keep a house empty. (Better still, we should return all land ownership to the commons, though I accept this may be a slightly less popular political project.)

The argument against second homes is a little complex - people who live in London during the week do spend money in the local economy, and save the emissions of a long daily commute - but it cannot be the case that one person or family occupying two homes is the fairest way to solve any problem.

There is such a shortage of key worker housing for Londoners who can neither afford to commute in every day nor to buy a first private home let alone a second one; and the obstacle to building more is not just money but space. The "right" of anyone to a second or, worse, an empty home must be secondary to the needs of people with nowhere to live, and of London's public services for skilled and diverse workers.