London mansions

The Labour Party's proposal for an additional property tax on houses worth more than two million pounds has, according to the New Statesman, been rejected by most of the party's potential candidates for the London mayoralty.

The details are a bit vague (to be polite), but Labour is briefing that there are around 100,000 such houses in the country. And of those, some 90 per cent are in London. That's 90,000 properties. Assuming two voters in each, that'd make 180,000 people with a fairly substantial interest in not voting Labour.

And, to put that in context, the only time that a Labour candidate won a mayoral election, Ken Livingstone beat Steven Norris in the second round in 2004 with a majority of just over 160,000.

Many of the properties that would be affected aren't actually occupied by anyone on the electoral register in Britain. And many of those who are part of the electorate are probably much not inclined towards Labour. But some are. And so are some of those who live in properties not far off those prices. It's an odd place like that, London. And although Labour are hot favourites to win back the mayoralty in 2016, there's not much margin for error.

Apart from all of which, the mansion tax proposal is still a poor substitute for adding, say, another five bands at the top of council tax.