THE “grubby” price for keeping Theresa May and the Conservatives in power has been set at a cool £1 billion by Northern Ireland’s Democratic Unionists – but Scotland is not expected to see any knock-on financial benefit.

The Con-DUP deal was struck just 72 hours before the Prime Minister faces a key Commons vote on getting her Queen’s Speech programme for government through. The backing of an extra 10 DUP MPs means Mrs May will have a working majority of 13 once the Speaker, the three Deputy Speakers and Sinn Fein’s seven MPs are taken out of the parliamentary arithmetic.

Immediately after being announced, the inter-party agreement was branded a “bung” and a “shoddy little deal” by opposing parties.

The Con-DUP pact will mean the Tory Government has been forced to abandon its manifesto plans to abolish the state pension triple-lock and means-testing the winter fuel payment south of the border during this Parliament.

Speaking after talks in No 10 with DUP leader Arlene Foster, Mrs May said the two parties "share many values" and the agreement was "a very good one".

Mrs Foster said she was "delighted" with a package which not only includes £1bn of new funding for infrastructure and health spending but also enhanced flexibility on almost £500 million of previously allocated cash.

There were immediate demands for other parts of the UK to receive similar largesse with Plaid Cymru saying Wales should be entitled to £1.7bn on a population-weighted basis. Under such a scenario, Scotland would look to see an extra £3bn while England would benefit by nearly £30bn.

Ian Blackford, the SNP leader at Westminster, said: "After weeks of secret backroom negotiations, the Tories have now signed a grubby deal with the DUP.

"The financial aspects of this deal entirely sum up how little the Tories care about Scotland while a billion pounds is being handed over to Northern Ireland, Scotland is seemingly to be offered little more than scraps from the table.”

The Highland MP said the claim was being made that the funding was a recognition of Northern Ireland's special circumstances but if there was any true appreciation of those circumstances, there would be no deal at all with the DUP.

"Only 24 hours ago David Mundell was categorically assuring us that Scotland would be in line for Barnett consequentials as a result of the DUP deal; so, he has seemingly either been deliberately misleading people or he is completely out of the loop even in Theresa May's crumbling government."

He said the deal was "the first big test" for Ruth Davidson, the Scottish Conservative leader, and her new raft of Scottish Tory MPs.

Kezia Dugdale, the Scottish Labour leader, said: “If the price of propping up this miserable Tory Government is hundreds of millions of pounds for Northern Ireland, it is vital that all nations and regions of the UK also get extra funding to end austerity.

"If Scottish Tory leader Ruth Davidson has any influence in Downing Street at all, she will be demanding extra cash to reverse the spending cuts her government has inflicted on Scotland aided and abetted by the SNP, which has simply turned Holyrood into a conveyer belt for Tory cuts.”

She added: “By attempting to secure her future by throwing money at one part of the UK, the Prime Minister’s deal risks weakening the bonds that unite the UK and shows how empty her rhetoric is about the future of the Union.”

Her Labour colleague, Carwyn Jones, the Welsh First Minister, said: "Today's deal represents a straight bung to keep a weak Prime Minister and a faltering Government in office.

"Only last week, we were told that the priority was to 'build a more united country, strengthening the social, economic and cultural bonds between England, Northern Ireland, Scotland and Wales'. This deal flies in the face of that commitment and further weakens the UK, and as currently drafted all but kills the idea of fair funding for the nations and regions.

"It is outrageous that the Prime Minister believes she can secure her own political future by throwing money at Northern Ireland whilst completely ignoring the rest of the UK. I have spoken to the Secretary of State for Wales this morning to clearly state my view at this unacceptable deal - as Wales' voice at the Cabinet table, he has a duty to fight against this deal and secure additional funding for our country."

Liz Saville Roberts, Plaid Cymru's leader in Westminster, said: "Despite Wales voting overwhelmingly to reject the Conservatives, we seem destined to be governed by the Conservatives once again, propped up by an extreme right-wing party opposed to gay rights, who criminalise women who have an abortion and is supported by armed terror groups.

"Our country did not vote for this Government and Plaid Cymru will oppose this Government at every step of the way.

"Any commitments for Northern Ireland should be matched for Wales. If reports that the DUP has secured a £1 billion increase in public spending in Northern Ireland are realised, Wales' population share would be around £1.7 billion - a substantial boost to the Welsh economy that must be delivered."

Meanwhile, the agreement was denounced as a "shoddy little deal" by Liberal Democrat leader Tim Last week, David Mundell, the Scottish secretary, declared: “Any funding that goes to Northern Ireland, then Barnett rules will ensure the appropriate funding comes to Scotland."

He added: "I'm not going to agree to anything that could be construed as back-door funding to Northern Ireland."

However, the Barnett Formula is usually predicated on departmental spending rises or falls for England with financial consequentials then being calculated on the basis of population in Scotland, Wales and Northern Ireland. A thumbnail rule is that Scotland gets around 10 per cent of what England receives.

Gerald Holtham, visiting professor of regional economy at Cardiff Metropolitan University, who has advised the Welsh Government, the Scottish Parliament and the Stormont Assembly on funding, said if Northern Ireland received extra money, then that did not mean Scotland, Wales and England would get a population share too.

Asked by the BBC recently if the Barnett Formula could work in reverse, Prof Holtham replied: “In a word No. The Barnett Formula works in one direction only.

“If the Government decides it’s going to do a formula bypass, which it has done on many past occasions, that’s what it does, The Barnett Formula has no legal basis. There’s no law which says you have to have a Barnett Formula; it’s a convention; it’s at the discretion of the minister. If he wants to bypass it, he will bypass it.”

Asked about other parts of the UK getting money on the back of the DUP deal, Prof Holtham said: “I don’t think there’s any possibility the UK Government will generalise any deal they do with Northern Ireland…People like the Scots might say that’s not fair but they have had plenty of bypasses in the past; so they’re not in a position to complain.”

He suggested the UK Government would do whatever they could “get away with, basically,” noting: “If the pressure for fairness is politically significant, then they might make concessions but they really don’t need to do so.”

Asked about the spending on such a scale outwith the formula, Prof Holtham referred to the various City deals the Government had implemented, which were “all outside the Barnett Formula”.

Damian Green, the first secretary of state, who will make a Commons statement on the Con-DUP deal this afternoon, noted how there had been five City Deals in Scotland.

Elsewhere, Tim Farron, the Liberal Democrat leader, said: "The public will not be DUPed by this shoddy little deal. The Nasty Party is back, propped up by the DUP.

"While our schools are crumbling and our NHS is in crisis, Theresa May chooses to throw cash at 10 MPs in a grubby attempt to keep her Cabinet squatting in No 10.

"It would be better for the people of Northern Ireland for the DUP to buckle down and focus on the talks process to restore devolved Executive at Stormont, to bring the political stability that is needed for inward investment and growth, rather than demanding cash injections from the Treasury."

Jonathan Bartley, the Green Party co-leader, said: "The coalition of cruelty deal has now been signed and the Tory Government stumbles on for another day.

"Theresa May's claim her party shares many of the DUP's values is alarming; which is she referring to? Their opposition to equal marriage, abortion or climate action? The Green Party will always stand up against the regressive values of the DUP and work with others to stop a lurch to the right under a Tory-DUP alliance."

The £1bn Con-DUP deal breaks down as follows:

*£400m for infrastructure projects [£200m per year for two years]; *£200m for improvement of health service [£100m per year for two years];

*£150m for ultra-fast broadband [£75m per year for two years];

*£100m for tackling deprivation [£20m per year for five years];

*£100m to address immediate pressures in health and education [£50m per year for two years] and

*£50m for mental health services [£10 million per year for five years].