
Why is the exit deal that Theresa May has negotiated so unsatisfying to Brexiteers? The short answer is: because in June 2017 she lost her parliamentary majority and had to strike a deal with the Democratic Unionist Party to remain in office.
The DUP doesn’t want a Brexit that treats Northern Ireland differently from the rest of the United Kingdom, while no Irish political party would be able to survive as a viable political project if it signed up to an accord that put a hard border through the island of Ireland. The Irish government, as with all member states of the European Union, has a veto over the final trade agreement with the United Kingdom.