Labour politicians in expensive parts of town are enjoying an observation reportedly made by Boris Johnson at the World Economic Development Forum in Davos. It seems the mayor has suggested Conservative Kensington and Chelsea follow Labour Camden by slapping large council tax increases on the owners of furnished properties that go uninhabited for more than two years.

Camden's cabinet member for finance Theo Blackwell writes that this led to a 35% reduction in the number of empty homes in his borough within nine months. He continues:

Camden, like neighbouring Westminster, Kensington and Chelsea and Hammersmith and Fulham has a high number of long-term empty homes. There is concern that properties are purchased but then left empty for quick sale as investments for wealthy overseas buyers. Seeing as property prices went up in Camden by 4.4% in one month alone, you can see why.

Enthused, Westminster's Labour Group leader Paul Dimoldenberg has renewed his call for the Tories who run his borough to do the same as Camden. And Blackwell points out that, while Johnson also advocated even bigger council tax hikes than Camden's should they be necessary, the government has turned down the borough's request to extend its policy to homes left empty for just one year rather than two.

The mayor's backing for swingeing tax hikes on property speculators may seem at odds with his general devotion to them. Yet, like his desire for measures against land banking, it shows that even as deep-dyed a free market evangelist as he knows London can't afford to let them have everything their own way. Not absolutely everything, anyway.