The exchanges between Boris Johnson and the DUP in the House of Commons on Saturday were short and terse, but they struck a loud death knell for the relationship of convenience that had existed between them.

DUP MPs ranted and raved with all the exasperation of a party that believed they hadn’t brought this on themselves.

The word “betrayal” hung in the air, and other words sprung to mind too:

“What a fool I was! I was only a puppet, and so was Ulster, and so was Ireland, in the political game that was to get the Conservative Party into power.”

This was not the cry of Arlene Foster after reading Boris Johnson’s new Brexit deal, but rather from a 1921 speech by Edward Carson, the grandfather of unionism. His party members were once again propping up Tory votes, only for the coalition government to oversee the partition of Ireland. Over the past century, despite their allegiance to Britain, Northern Ireland’s unionists have often feared another betrayal of British politicians.

Violence erupts in Northern Ireland as journalist killed during riots Show all 21 1 /21 Violence erupts in Northern Ireland as journalist killed during riots Violence erupts in Northern Ireland as journalist killed during riots A burning car in Creggan, Derry after petrol bombs were thrown at police during riots in Northern Ireland PA Violence erupts in Northern Ireland as journalist killed during riots Armed police at the scene of unrest PA Violence erupts in Northern Ireland as journalist killed during riots Petrol bombs being thrown at police PA Violence erupts in Northern Ireland as journalist killed during riots Belfast Journalist Lyra McKee was killed during the riots. Police Service of Northern Ireland said that McKee was allegedly shot while reporting on clashes with dissident republican rioters EPA Violence erupts in Northern Ireland as journalist killed during riots A burning car in Creggan, Londonderry after petrol bombs were thrown at police. PRESS ASSOCIATION Photo. Picture date: Thursday April 18, 2019. Photo credit should read: Niall Carson/PA Wire Niall Carson PA Violence erupts in Northern Ireland as journalist killed during riots Armed police in Creggan, Londonderry after shots were fired and petrol bombs were thrown at police. PRESS ASSOCIATION Photo. Picture date: Thursday April 18, 2019. Photo credit should read: Niall Carson/PA Wire Niall Carson PA Violence erupts in Northern Ireland as journalist killed during riots Armed police in Creggan, Londonderry after shots were fired and petrol bombs were thrown at police. PRESS ASSOCIATION Photo. Picture date: Thursday April 18, 2019. Photo credit should read: Niall Carson/PA Wire Niall Carson PA Violence erupts in Northern Ireland as journalist killed during riots Petrol bombs are thrown at police in Creggan, Londonderry. PRESS ASSOCIATION Photo. Picture date: Thursday April 18, 2019. Photo credit should read: Niall Carson/PA Wire Niall Carson PA Violence erupts in Northern Ireland as journalist killed during riots Armed police in Creggan, Londonderry after shots were fired and petrol bombs were thrown at police. PRESS ASSOCIATION Photo. Picture date: Thursday April 18, 2019. Photo credit should read: Niall Carson/PA Wire Niall Carson PA Violence erupts in Northern Ireland as journalist killed during riots Heavilly armed police guard a crime scene during unrest in the Creggan area of Londonderry. PRESS ASSOCIATION Photo. Picture date: Thursday April 18, 2019. See PA story . Photo credit should read: Niall Carson/PA Wire Niall Carson PA Violence erupts in Northern Ireland as journalist killed during riots Hijacked vehicles on fire in Creggan, Londonderry. PRESS ASSOCIATION Photo. Picture date: Thursday April 18, 2019. Photo credit should read: Niall Carson/PA Wire Niall Carson PA Violence erupts in Northern Ireland as journalist killed during riots Armed police in Creggan, Londonderry after shots were fired and petrol bombs were thrown at police. PRESS ASSOCIATION Photo. Picture date: Thursday April 18, 2019. Photo credit should read: Niall Carson/PA Wire Niall Carson PA Violence erupts in Northern Ireland as journalist killed during riots hijacked vehicles one fire in Creggan, Londonderry. PRESS ASSOCIATION Photo. Picture date: Thursday April 18, 2019. Photo credit should read: Niall Carson/PA Wire Niall Carson PA Violence erupts in Northern Ireland as journalist killed during riots Petrol bombs are thrown at police in Creggan, Londonderry. PRESS ASSOCIATION Photo. Picture date: Thursday April 18, 2019. Photo credit should read: Niall Carson/PA Wire Niall Carson PA Violence erupts in Northern Ireland as journalist killed during riots Petrol bombs are thrown at police in Creggan, Londonderry. PRESS ASSOCIATION Photo. Picture date: Thursday April 18, 2019. Photo credit should read: Niall Carson/PA Wire Niall Carson PA Violence erupts in Northern Ireland as journalist killed during riots A hijacked car explodes after being set on fire in Creggan, Londonderry. PRESS ASSOCIATION Photo. Picture date: Thursday April 18, 2019. Photo credit should read: Niall Carson/PA Wire Niall Carson PA Violence erupts in Northern Ireland as journalist killed during riots A PSNI officer conducts a search after shots where reportedly fired in Creggan, Londonderry. PRESS ASSOCIATION Photo. Picture date: Thursday April 18, 2019. Photo credit should read: Niall Carson/PA Wire Niall Carson PA Violence erupts in Northern Ireland as journalist killed during riots The scene of unrest in Creggan, Londonderry. PRESS ASSOCIATION Photo. Picture date: Thursday April 18, 2019. Photo credit should read: Niall Carson/PA Wire Niall Carson PA Violence erupts in Northern Ireland as journalist killed during riots Police conduct a crime scene search after shots where fired in Creggan, Londonderry. PRESS ASSOCIATION Photo. Picture date: Thursday April 18, 2019. Photo credit should read: Niall Carson/PA Wire Niall Carson PA Violence erupts in Northern Ireland as journalist killed during riots The scene on Fanad Drive the following day PA Violence erupts in Northern Ireland as journalist killed during riots The scene on Fanad Drive in Londonderry, Northern Ireland, following the death of 29-year-old journalist Lyra McKee who was shot and killed when guns were fired and petrol bombs were thrown in what police are treating as a "terrorist incident". PRESS ASSOCIATION Photo. Picture date: Friday April 19, 2019. See PA story ULSTER Unrest. Photo credit should read: Brian Lawless/PA Wire Brian Lawless PA

They were right to worry. In 1985, the DUP led unionist outrage after the signing of the Anglo-Irish Agreement, which gave Dublin a say in the running of Northern Ireland. The party leader Ian Paisley blasted Margaret Thatcher as a traitor, and oversaw the burning of her effigy. In a letter, he told her, “You have prepared Ulster Unionists for sacrifice on the altar of political expediency.”

When the DUP threw their support behind the Brexit campaign in 2016 – in keeping with their lifelong opposition to the EU – they were setting themselves up for another Great British disappointment. Many in Northern Ireland, including the majority who backed remaining in the EU, warned the DUP that this could only end badly for the region, and the union. They didn’t listen.

In June 2017, as the DUP walked up Downing Street to secure their confidence and supply deal with Theresa May, they were being led down the garden path. In exchange for propping up the Conservatives, they were handsomely rewarded with £1 billion. But their hubris led them to believe that they could also steer the government towards a Brexit of their own liking.

When it became clear that Northern Ireland’s special circumstances were preventing Britain from achieving the Brexit which most leavers envisaged, it was inevitable that Northern Ireland would have to be treated differently. As people on all sides (the DUP included) rejected a border on the island of Ireland, quite simply, there would have to be some sort of a border in the Irish Sea.

Theresa May claimed she couldn’t accept this, and opted for a deal which put all of the UK in a backstop, rather than just Northern Ireland. At this point, with the prospect of the entire UK leaving as one, the DUP should have counted their blessings. But instead, they overplayed their hand, pushing for a harder Brexit which could not be delivered without Northern Ireland being treated differently.

Foolishly, the DUP plotted May’s downfall, while courting more hardline Tories, like the ERG and Boris Johnson – who were certainly more hardline on Brexit, but not, as it turned out, on the union. And who could be surprised?

Despite being called the Conservative and Unionist Party, polls show that party members value Brexit over maintaining the union. Alarmingly, a majority even believe that Brexit matters more than maintaining peace in Northern Ireland. The message to unionists from the mainland is as disappointing today as it was in the days of Carson – they’re just not interested.

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Ironically, despite going over the heads of the DUP, the Tories have actually come up with something which is a reasonable compromise for Northern Ireland. If Brexit has to happen, then this deal is the best possible outcome for us.

Foreign Secretary Dominic Raab even espoused the amazing potential it has to give Northern Ireland special access to the EU market; causing many in Britain to wonder why the rest of us won’t receive the same benefit. But even this final financial incentive left the DUP unconvinced, so concerned are they now for the union which they themselves imperiled.