"Brown's mistake" has already been reversed

The personal allowance has grown to undo any losses the abolition of the 10p rate inflicted.

Ed Miliband has committed to introducing a mansion tax, and using the money to fund a re-introduction of the 10p tax band, saying:

We would tax houses worth over £2 million. And we would use the money to cut taxes for working people. We would put right a mistake made by Gordon Brown and the last Labour government. We would use the money raised by a mansion tax to reintroduce a lower 10 pence starting rate of tax, with the size of the band depending on the amount raised. This would benefit 25 million basic rate taxpayers.

The original 10 pence tax band was applied on incomes between £0 and £2,230, once the personal allowance was taken into account. Its abolition was used to fund the reduction in the basic rate of tax from 22p to 20p. But while Miliband says he will "put right [the] mistake made by Gordon Brown", he's not going to be reversing the basic rate cut. Instead, the money will come from the mansion tax.

But the Social Market Foundation's Ian Mulheirn points out that that mansion tax is not expected to raise anywhere near as much as two per cent on the basic rate of tax would. He tells me that their expectation for a mansion tax on houses over £2m is in the low billions — probably around £2bn or £3bn.

But every billion pounds raised would only pay for a 10p tax band of between two and three hundred pounds, he says:

We've got about 30 million income taxpayers in the UK, once you take the personal allowance into account. Assuming that they all would benefit by the full amount, then if you've got £1bn to play with, you could have a tax band of about £330.

A tax band of £330 would return £33 to each taxpayer. If the mansion tax raises the high end of estimates, then the band could be around £1000, returning £100 to each taxpayer. That's not to be sniffed at, but it's less than half of the size of the abolished band. It's not putting right Brown's mistake, but it ameliorates it slightly.

But actually, Brown's mistake has already been largely put right.

In 2007, the last year of the 10p tax rate, the personal allowance stood at £5,035. With the 10p band on top, basic rate tax started at £7,265. Uprated for inflation, that will be worth slightly under £9000 in the tax year starting in 2013.

In that same year, the personal allowance will stand at £9,440. Someone who would in 2007 have been paying only the 10p tax rate is today paying no tax at all. Miliband's actions, if introduced in 2015, will likely introduce a reduced tax rate for people earning between £10,000 and £11,000 to complement a zero tax rate for people earning less than that. That's likely a good thing; but it's a new thing, not a reversal of Brown's actions. They have already been undone.

Of course, if you have to delve into uprating tax bands by inflation to prove a point, it's not going to fly very well in political debates. That's why, as George writes, politically, the move is a masterstroke.

Brown walks through Rugby. Photograph: Getty Images

Alex Hern is a technology reporter for the Guardian. He was formerly staff writer at the New Statesman. You should follow Alex on Twitter.

How Jim Murphy's mistake cost Labour - and helped make Ruth Davidson

Scottish Labour's former leader's great mistake was to run away from Labour's Scottish referendum, not on it.

The strange revival of Conservative Scotland? Another poll from north of the border, this time from the Times and YouGov, shows the Tories experiencing a revival in Scotland, up to 28 per cent of the vote, enough to net seven extra seats from the SNP.

Adding to the Nationalists’ misery, according to the same poll, they would lose East Dunbartonshire to the Liberal Democrats, reducing their strength in the Commons to a still-formidable 47 seats.

It could be worse than the polls suggest, however. In the elections to the Scottish Parliament last year, parties which backed a No vote in the referendum did better in the first-past-the-post seats than the polls would have suggested – thanks to tactical voting by No voters, who backed whichever party had the best chance of beating the SNP.

The strategic insight of Ruth Davidson, the Conservative leader in Scotland, was to to recast her party as the loudest defender of the Union between Scotland and the rest of the United Kingdom. She has absorbed large chunks of that vote from the Liberal Democrats and Labour, but, paradoxically, at the Holyrood elections at least, the “Unionist coalition” she assembled helped those parties even though it cost the vote share.

The big thing to watch is not just where the parties of the Union make gains, but where they successfully form strong second-places against whoever the strongest pro-Union party is.

Davidson’s popularity and eye for a good photo opportunity – which came first is an interesting question – mean that the natural benefactor in most places will likely be the Tories.

But it could have been very different. The first politician to hit successfully upon the “last defender of the Union” routine was Ian Murray, the last Labour MP in Scotland, who squeezed both the  Liberal Democrat and Conservative vote in his seat of Edinburgh South.

His then-leader in Scotland, Jim Murphy, had a different idea. He fought the election in 2015 to the SNP’s left, with the slogan of “Whether you’re Yes, or No, the Tories have got to go”.  There were a couple of problems with that approach, as one  former staffer put it: “Firstly, the SNP weren’t going to put the Tories in, and everyone knew it. Secondly, no-one but us wanted to move on [from the referendum]”.

Then again under different leadership, this time under Kezia Dugdale, Scottish Labour once again fought a campaign explicitly to the left of the SNP, promising to increase taxation to blunt cuts devolved from Westminster, and an agnostic position on the referendum. Dugdale said she’d be open to voting to leave the United Kingdom if Britain left the European Union. Senior Scottish Labour figures flirted with the idea that the party might be neutral in a forthcoming election. Once again, the party tried to move on – but no-one else wanted to move on.

How different things might be if instead of running away from their referendum campaign, Jim Murphy had run towards it in 2015. 

Stephen Bush is special correspondent at the New Statesman. His daily briefing, Morning Call, provides a quick and essential guide to British politics.

0800 7318496