The outcome is unlikely to change, but another EU customs union vote would honour Jo Swinson following pairing arrangement failures

There is a mood for change in parliament, and righteous anger. And yet, the Commons has not even fully debated the issues

Someone is being economical with the actualité. The Conservatives say that the breaking of a pairing arrangement with a Liberal Democrat MP in a vital vote on Brexit was a mistake. The prime minister herself told the leader of the Opposition that in the House of Commons during question time. She apologised. The leader of the House of Commons, Andrea Leadsom, repeated that it was an error, and again apologised.

The Tory MP concerned is Brandon Lewis, who also happens to be the chairman of the party. He has apologised to the liberal Democrat MP, Jo Swinson, a new mother. In the Commons, the Liberal Democrat chief whip, Alistair Carmichael, accepted the apology. Theresa May and Ms Leadsom appeared sincere in their regrets and their belief that what went ahead was not good enough. But they need to do more.

And yet, the affair refuses to go away. Allegations have now been made that the Conservative chief whip, Julian Smith, told his colleagues to break pairings so as to defeat a rebel/Labour amendment on the customs bill. The allegations are being denied. But someone must be wrong, even if mistakes were made. There are witnesses to what Mr Smith said, it is claimed, but they have not yet come forward. Two other Conserve MPs had, it is alleged, been pressured to break a pairing – a serious parliamentary offence. On taking further advice, they refused to do so.

The immediate question facing the Commons authorities and the “usual channels” is to determine the truth about this vote, if need be through some form of amnesty for the “witnesses”. It would be perfectly in order for the Speaker’s Office to take an interest in this, again with the consent of the house as a whole. Women MPs especially, but many men, are outraged by what may be a grave abuse of parliamentary conventions, and a gender discriminatory one at that, given that it relates to a female MP on maternity leave. Such are the dynamics of a tight vote that the circumstances and atmosphere in the lobbies surrounding it can determine the outcome – it is not a simple matter of arithmetic. If the whips persuade MPs that a dissident vote is lost for them anyway, they are more likely to fall into line, for example.

This was one such occasion, and a crucial one too. The Commons rises for its long summer recess shortly; but there is still time, to borrow a phrase, for this vote to be saved in the sense of it being put beyond accusations that the vote was “stolen” by sharp practice. The easiest thing would be to rerun the vote. The outcome is unlikely to be different, but it would remove a nagging doubt about the validity of a vote of enormous import – one that might have kept the UK in the EU customs union after Brexit. House of Commons speaker John Bercow should lobby for a fresh division. Mr Lewis should consider his position.

The incident highlights the need for reform of the Commons’ archaic procedures. Pairing may still form a useful part of future arrangements, though it perhaps needs a greater degree of formality and clarity in individual cases. What would be more satisfactory is a measure that can cover maternity leave and some other defined circumstances in which it makes little sense to force the chamber to go through the lobbies or be otherwise on the parliamentary state in order to make their mark on certain proposals. There are too many cases of seriously ill MPs being forced inside in ambulances or wheelchairs. It is a matter for the House of Commons and the speaker to order their affairs, not ministers as such. There is a mood for change in Parliament, and righteous anger about what happened to Jo Swinson. What is so disappointing is that the Commons has not even fully debated the issues yet.

There will be many more tight votes in the Commons in the coming months, and much opportunity for arm-twisting, sharp practice and shenanigans on all aides. For the sake of a country already badly divided on the issue, the Commons owes it to the voters, and to itself, to make sure that it at least looks honest in its dealings. Time for the MPs to take back control – of their own whips.