The latest Brexit drama in parliament is a sign MPs simply do not trust the prime minister to keep her word

There is nothing intrinsically ridiculous about a vote in the House of Commons ending in a tie. It is rare, and result is determined by the casting vote of the speaker, based on well-established precedents which err towards the status quo.

Where the Commons tied vote acquires its satirical edge is the fact that it was a vote about voting – allocating more parliamentary time for the “indicative votes” process to continue. Thus our MPs showed their constituents and indeed the whole world that they cannot even decide about how to decide Brexit. It really is that bad.

Fortunately, the cross-party backbench bill tabled by Yvette Cooper and Oliver Letwin to outlaw a no-deal Brexit scraped through on a majority of one to win some time for debate, the first stage on a perilous and desperately pressured journey towards the statute book. It deserves to succeed.

Yet, if the prime minister is to be believed, neither of these parliamentary procedures is in fact strictly necessary.

Theresa May has publicly ruled out a no-deal Brexit, on the grounds that parliament has already voted overwhelmingly to that effect, even though it remains the legal default position for 12 April.

In her most recent statement, Ms May has also promised to hold indicative votes which she herself would honour, depending on the outcome of her talks with Jeremy Corbyn.

Unlike previous half-hearted attempts to forge a consensus across the front benches, these do seem to be at least off to a practical and constructive start, with teams on both sides setting about their work. It is a novel and reassuring development. The teamwork could develop into, in essence, a national unity administration limited to the Brexit issue.

However, the deeper danger, of course, is that the two leaderships will conspire to deprive the British people of their final say on the terms of Brexit. That really would be a Brexit betrayal. It is this concern that has led Labour MPs to write an open letter to Mr Corbyn in The Independent saying “it would be untenable for Labour not to insist” on one. Mr Corbyn’s frontbench team, major trade unions, Labour MPs and, crucially, party members expect him to insist on a Final Say public vote.

Parliament, then, should remain vigilant and continue to assert itself through its own, independent indicative vote process. In principle, therefore, the Commons could mandate the prime minister to negotiate a customs union with the European Union as a part of the withdrawal agreement package, and to organise a second referendum so that the outcome of these extended Brexit talks can be put to the people.

The fact that so many MPs, on all sides of the house, are persisting with their efforts to guarantee that there will not be a no-deal Brexit and to continue their deliberations about a Brexit compromise suggests that they do not trust Ms May to keep her word.

In part this is her own fault. Recently it has become routine for ministers to ignore parliamentary debates and allow motions to be carried with no Conservative MPs going through the lobbies – showing a thoroughly contemptuous attitude.

Why then should MPs think that Ms May will pay any more attention to their motions now? The country needs legal guarantees, and internationally enforceable legal guarantees about its future. Most of all the will demand a guarantee that they will get their final say over Europe.