Will Theresa May call the DUP’s bluff on Brexit?

The threat that the DUP might vote against the Budget if it isn’t happy with where the Irish border backstop is after the October European Council all fits with their effort to persuade Number 10 that they really are serious. As I say in tomorrow’s Spectator, some in government believe that, ultimately, May is going to have to call the DUP’s bluff on extra regulatory checks in the Irish Sea.