For all the attention on the Independent Group of former Labour and Conservative MPs, Theresa May’s fragile grip on the Brexit process was almost — but not quite — removed by a different cross-party alliance this week.

The Labour MPs Yvette Cooper and Hilary Benn and the Conservatives Sir Oliver Letwin and Nick Boles wanted to seize control of the parliamentary agenda to force a relaxation of the prime minister’s red lines. Their manoeuvre failed by two votes after a week of infighting over strategy.

For several months the core of the alliance have been meeting almost daily, with a larger meeting of the group about once a week. Their cross-party approach was always likely to be tested by tribal loyalties, and it was these