Can anything rescue Theresa May’s reputation from this week’s DUP fiasco? There is not the remotest public interest in political blackmail and bribery, in grinding self-interest, in the dollop of £540 a head to Northern Irish voters who are already subsidy addicts. It merely tells us what two years in No 10 costs these days: a billion pounds of other people’s money.

Of course pork barrel politics is not new, even in Britain. In a similar predicament in 1978-9, Labour’s Jim Callaghan wrestled the same demons in trying (and failing) to buy off the Ulster Unionists. This was despite offering them five more seats in parliament. Callaghan still fell.

Theresa May faces backlash from Scotland and Wales over £1bn Tory-DUP deal Read more

Britain does at least now have a government marginally more secure in seeing the Brexit talks under way. Though the DUP deal makes little difference. The unionists have agreed only to stave off another general election for two years, and it is hard to believe they would have done otherwise. May was clearly desperate for a parliamentary comfort blanket.

The unionists have warned they will be back in two years’ time, and they will not be back for nothing. When Ethelred the Unready paid the Danegeld tax to the Viking Sweyn Forkbeard in 991, Forkbeard returned time and again. After five years he demanded six times as much and bankrupted the country.

The good news is that May and her chancellor, Philip Hammond, must now admit that public spending does indeed grow on magic money trees. At least it does if your political life is at stake. So why not other people’s lives? What about patients, schoolchildren, the elderly, the mentally ill, the inhabitants of tower blocks? Thank you, Hammond, and we’ll be back for more next year.

Some idea of the true scale of the Northern Ireland deal is emerging. Its citizens already get 21% more in state spending than the UK average. The same generosity in proportion to GDP would mean almost £60bn splurged over the UK as a whole. You could get a second high-speed train for that.

English MPs are famously weak when it comes to lobbying, but a hung parliament is open season for pork barrel localism

The DUP deal goes farther than the initial £1bn of goodies. It halts the means-testing of winter fuel grants. It means dropping what experts felt were reasonable changes in the pension calculation. Add on possible Northern Ireland-only tax cuts and the knock-on effect of all this on the Barnett funding formula for Scotland and Wales, and you soon get to £10bn.

The political discipline of austerity, shaky since May came to office, has thus collapsed. Northern Ireland wanted, and got, only the same cash for its clinics, schools, housing and transport projects that every local authority wants. May and Hammond cannot find the money by slashing a billion from some other spending budget. If they can borrow for Northern Ireland, why not for England, Scotland and Wales?

Others can now play the DUP game. Every MP has a “Belfast transport hub” in their constituency. Most desperately need a promised “uplift” for their local schools and hospitals. There are 21 Tory MPs in London and 13 in Scotland – more than there are DUP MPs. They could play the same game.

We could see marauding packs of anti-May Conservatives, eager to ingratiate themselves with their voters before a possible early election. Voters mind less about cuts to defence, justice or Whitehall than about losing their libraries, nurseries and old people’s services. English MPs are famously weak when it comes to lobbying, but a hung parliament is open season for pork barrel localism.

How should the prime minister respond? Her past eagerness to open a new chapter, post-austerity, and Hammond’s relaxed approach to the deficit, can now be taken at their word. Neither has anything to lose.

May should take Scots and Welsh protests to heart, abolish the clunky Barnett formula and invite opposition parties to help find a new deal for devolved government across the whole union – including English cities and counties. Rather than dismiss George Osborne’s “northern powerhouse” out of pique, she should make it her own. She should extend the concept of provincial re-invigoration to Yorkshire, the north-east and the Midlands – where a rising Tory, Andy Street, won the mayoralty last month.

The greatest distortion to the British economy, and therefore the greatest threat, is its dependence on the south-east and the capital. The best thing May could do, however short her stay in Downing Street, is start correcting this. She has to make “anywhere-but-London” the place that bright young people will want to be for a stimulating and prosperous career.

This goes beyond infrastructure investment. Buzz must be injected into living outside the capital. Four of the six megaprojects criticised as ill-conceived in today’s Institute for Government infrastructure report are in the capital. May should put London glamour on hold, and aggressively spend any money saved in the north.

This shoddy DUP deal will ultimately cost Theresa May far more than £1bn | Martin Kettle Read more

A first inkling of such a shift came with this week’s announcement, not before time, that London’s big arts institutions would be expected to stand more on their own feet. Austerity has devastated provincial culture. Under Nicholas Serota’s new Arts Council regime, the north is to get more and London’s Royal Opera, National Theatre and South Bank are to get less. They are booming. This is fair.

May should liberate local democracy to repair some of the damage done by austerity. She could boost the grant formula to local government, which at present she intends to go on cutting until 2020. Or better, she should put the clock back to the pre-Thatcher Tory party and give councils freedom to raise local taxes as far as their electors permit. The new British Social Attitudes survey suggests a rising public tolerance of “tax and spend”. The Tories could avoid the odium of raising income tax by allowing more steeply progressive local property taxes to rescue local services. Whitehall’s role should be limited to ensuring revenue redistribution from rich to poor areas.

May has bought herself two years of office. Two years is a long time in government. She can capitalise on her “vote of confidence” in Northern Ireland by extending it to the rest of the union. She can put confidence back into all of provincial Britain.