Theresa May and Arlene Foster posed Monday morning for photographs outside Downing Street. The thin smile on the British prime minister’s face looked rather forced. The Democratic Unionist Party (DUP) leader, in contrast, beamed in the morning sun.

The DUP — often depicted as the dourest of political parties — has every reason to be cheerful. The hardline unionists have secured more than £1 billion in extra funding for Northern Ireland over two years in return for propping up May’s minority government through a "confidence and supply" arrangement. The Conservative leader said the deal was “a good one” but few doubt that the DUP is the real winner.

Northern Ireland is set to receive more cash for roads, hospitals and other infrastructure projects. Corporation tax could be devolved to the Belfast legislature, and money made available for broadband, education and agriculture.

The DUP deal also gives May a chance to ditch some of the least popular elements of her manifesto, including plans to means test winter fuel payments for the elderly and proposals to alter the so-called triple lock on pensions. The Tories have also agreed to continue to meet the 2 percent NATO spending commitment.

The DUP’s 10 MPs will support the vote on the Conservatives’ queen’s speech this week and give their backing "on all motions of confidence," including the budget and finance bills. Most crucially, the unionists will give backing to all Brexit legislation.

As Sinn Féin don't take their seats in Westminster, May now has — at least on paper — a working majority of 13 Brexit votes.

The Conservatives’ decision to pursue an alliance with the DUP has been heavily criticised, with even some senior Tories wary of association with a party that has espoused extremely socially conservative positions far outside the U.K. political mainstream on everything from abortion and gay marriage to creationism.

Reacting to the news Monday, former Conservative deputy leader Michael Heseltine said the agreement was “not a long term solution.” The terms of the deal itself suggest many in the DUP and the Tory government agree — the agreement is “in place for the length of the parliament” but almost all the major spending commitments cover only the next two years.

Here are four main takeaways on the Tory-DUP deal:

1. More pork for Northern Ireland

By any measure, the increased spending commitments are significant. The Northern Irish block grant is set to rise by more than 5 percent per annum plus an additional £500 million in extra borrowing flexibility for the devolved government. Northern Ireland already has the highest per capita public spending in the U.K. This disparity is partly a reflection of the 30-year-long Troubles and decades of sluggish economic growth that has left the region with dilapidated infrastructure. The health service has been under particular strain.

Monday’s deal includes £200 million to "transform" the Northern Irish health service, as well as an additional £50 million a year for the next two years to address immediate pressures in health and education as well as £50 million for mental health. There will also be £200 million a year on infrastructure spending, with much of this likely to be targeted at a major road project in north Belfast. Another £150 million has been found to deliver super-fast broadband across the region.

Foster said her aim had been to "deliver for all the people of Northern Ireland," not just her unionist electorate. But the deal is likely to lead to demands for more pork from the rest of the UK, too. Under the funding conventions for the devolved administrations — the so-called Barnett formula — any increase in spending in one region is normally matched in the others. With this in mind, the Conservatives’ Scottish secretary David Mundell explicitly promised "no backdoor funding" for Northern Ireland earlier this month unless other devolved regions benefitted too.

There is little prospect of more cash for Scotland or Wales, but the Scottish National Party, Plaid Cymru (the Welsh nationalist party) and Labour are likely to point out the disparity at every opportunity.

2. Peace process

There has been no devolved government in Belfast since Northern Ireland’s power-sharing administration collapsed around the turn of the year. In the longest section of the DUP-Tory agreement, both parties state their "desire" to see devolution restored. Talks between the republicans and unionists are on-going this week. If no deal is in place by Thursday, Northern Ireland could revert to direct rule from London.

The language of the agreement with the Conservatives is avowedly unionist and includes some red meat DUP demands such as the extension of the military covenant to Northern Ireland and a commitment that investigations into killings committed during the Troubles will not "unfairly focus" on the police and armed forces. Such rhetoric will not go down well among Irish nationalists.

The Conservatives’ reliance on unionists' votes in London could increase instability in Northern Ireland because of suspicions about the government's neutrality. “If the British government was drawn into issues where its integrity was called into question — say the parades commission resigned and the secretary of state had to make decisions on parades — then it would become very difficult,” said Jonny Byrne, lecturer in politics at the University of Ulster.

3. Brexit

The DUP campaigned for Brexit, and the party’s commitment to support the Conservative government’s Brexit legislation brings the deal beyond the standard limits of a confidence and supply arrangement. As Sinn Féin don't take their seats in Westminster, May now has — at least on paper — a working majority of 13 Brexit votes. But the DUP’s position on Brexit has been at best ambivalent, maintaining that the EU should leave the customs union and the single market but there should be no significant changes to the Irish border.

The DUP identify agriculture as a "critical policy" area during the EU talks, a move that will be taken by some as the party’s willingness to accept a soft Brexit. The Northern Irish economy is far more reliant on farming than the rest of the U.K., and smallholders make up a significant section of the DUP’s core support. But there remains suspicion that some senior figures in the party would not oppose a hard border in practice, especially if it was felt that the EU could be blamed for its imposition.

The DUP, however, is not the only faction May has to worry about in government. Many of her own MPs back a softer approach to Brexit. That the DUP deal took weeks rather than the promised hours is likely to have antagonized the Tories’ liberal wing still further.

4. No sign of social conservatism

By almost any description, the DUP holds some pretty extreme views. The party — which emerged from a Protestant sect in the 1970s — is fervently anti-abortion and has opposed same-sex marriage. Senior figures have decried climate change as a myth and have even suggested that God created the world 6,000 years ago.

When the DUP emerged as kingmakers after the general election resulted in a hung parliament there were dire warnings from some quarters that the party would seek to impose their social conservative vision across the UK. Such fears were always likely to be misplaced and there is no hint in the agreement with the Tories of a more socially conservative line for the government. Over a decade in government, the DUP has shown itself to be a pragmatic party. Rather than using the deal with the Tories to ban abortion across Britain, the DUP's involvement in government has ended up securing guarantees for pensioners.