It was Labour who first suggested that the Commons start its summer break five days earlier than planned. Conservative whips, desperate to head off a vote of confidence in Theresa May as party leader, seized on Labour’s idea with delight. Then Labour pulled the plug, leaving the government red-faced. Amid more damaging headlines for May, the “Tory plan” was abandoned.

If Labour laid a trap, as senior Tories believe, then it was just about within the rules of the Westminster game. But Labour’s wicked whippery was pretty minor when compared with the apparent skulduggery of Julian Smith, the government chief whip.

The biggest issues facing UK on leaving EU Show all 8 1 /8 The biggest issues facing UK on leaving EU The biggest issues facing UK on leaving EU Post-Brexit immigration workers sorting radishes on a production line at a farm in Norfolk. One possible post-Brexit immigration scheme could struggle to channel workers towards less attractive roles - while another may heighten the risk of labour exploitation, a new report warns. PA The biggest issues facing UK on leaving EU Customs union A key point in the negotiations remains Britain's access to, or withdrawal from, the EU customs union. Since the referendum there has been hot debate over the meaning of Brexit: would it entail a full withdrawal from the existing agreement, known as hard Brexit, or the soft version in which we would remain part of a common customs area for most goods, as Turkey does? No 10 has so far insisted that “Brexit means Brexit” and that Britain will be leaving the customs union, but may be inclined to change its position once the potential risks to the UK’s economic outlook become clearer. Alamy The biggest issues facing UK on leaving EU Northern Ireland-Irish border Though progress was made last year, there has still been no solid agreement on whether there should be a hard border between Northern Ireland and the Republic of Ireland. To ensure borderless travel on the island, the countries must be in regulatory alignment and therefore adhere to the same rules as the customs union. In December, the Conservative Party’s coalition partners, the DUP, refused a draft agreement that would place the UK/EU border in the Irish Sea due to its potential to undermine the union. May has promised that would not be the case and has suggested that a “specific solution” would need to be found. Getty The biggest issues facing UK on leaving EU Transition period Despite protests from a small number of Conservative MPs, the Government and the EU are largely in agreement that a transitional period is needed after Brexit. The talks, however, have reached an impasse. Though May has agreed that the UK will continue to contribute to the EU budget until 2021, the PM wants to be able to select which laws made during this time the UK will have to adhere to. Chief negotiator Michel Barnier has said the UK must adopt all of the laws passed during the transition, without any input from British ministers or MEPs. EPA The biggest issues facing UK on leaving EU Rights of EU citizens living the UK The Prime Minister has promised EU citizens already living in the UK the right to live and work here after Brexit, but the rights of those who arrive after Brexit day remains unclear. May insists that those who arrive during the transition period should not be allowed to stay, whereas the EU believe the cut-off point should be later. Getty The biggest issues facing UK on leaving EU Future trade agreement (with the EU) Despite this being a key issue in negotiations, the Government has yet to lay out exactly what it wants from a trade deal with the EU. Infighting within the Cabinet has prevented a solid position from being reached, with some MPs content that "no deal is better than a bad deal" while others rally behind single market access. The EU has already confirmed that access to the single market would be impossible without the UK remaining in the customs union. Getty The biggest issues facing UK on leaving EU Future trade agreements (internationally) The Government has already begun trying to woo foreign leaders into prospective trade agreements, with various high profile state visits to China, India and Canada for May, and the now infamous invitation to US President Donald Trump to visit London. However the UK cannot make trade agreements with another country while it is still a member of the EU, and the potential loss of trade with the world's major powers is a source of anxiety for the PM. The EU has said the UK cannot secure trade deals during the transition period. EPA The biggest issues facing UK on leaving EU Financial services Banks in the UK will be hit hard regardless of the Brexit outcome. The EU has refused to give British banks passporting rights to trade within the EU, dashing hopes of a special City deal. However according to new reports Germany has suggested allowing trade on the condition that the UK continues paying into the EU budget even after the transition period. Getty

It has been reported that he told up to five Tory MPs to break the pairing arrangement under which they and an opposition MP agreed to miss Tuesday’s knife-edge vote on remaining in a customs union after Brexit. Only one MP broke their deal; that four Tories defied their own chief whip shows how he crossed a line. Pairing is informal but suits all parties, as MPs will inevitably miss some votes. It helps a government more than an opposition, and is even more vital in a hung parliament.

This might sound like another Westminster bubble story that doesn’t matter in the real world. But this one does. Smith claims his only mistake was to tell Brandon Lewis, the Tory chairman, to take part in two crunch votes (but not others) while paired with Jo Swinson, the Liberal Democrats’ deputy leader, who is on maternity leave. It’s not a good look for the Tories, who are already going down in the opinion polls amid bitter divisions over Europe, and now appear untrustworthy and nasty.

To make matters worse for Smith, he has embroiled May in the scandal. She told MPs on Wednesday: “the breaking of the pair was done in error”, apparently unaware that Smith had told other MPs to do so. Andrea Leadsom, the Commons leader, told the House it was “an administrative error”. If the Commons has been misled, it matters. Many Tory MPs, including ministers, are rightly outraged by Smith’s behaviour. He was the talk of the town at Westminster’s summer parties, and not in a flattering way.

In 36 years as a Westminster journalist, I’ve seen the tricks of the whips’ trade. They used to keep a “black book” of rumours about MPs, listing their affairs, visits to gay clubs and other extracurricular activities, and used to threaten them when a tricky vote loomed. Whips did not even care if the gossip was true. They’ve been known to threaten journalists in similar vein. Less is written down these days, and records are shredded after a while, so they cannot be called as evidence in court. But threats are still made. Then there are the loyalty tests. An old trick is to send an email or note marked “to all Tory MPs” to just one suspected leaker to see if it is passed to the media. Neat.

Smith’s actions this week are beyond the pale. Of course, he was under intense pressure. In response to the pairing debacle, a party spokesman said: “We have apologised for the fact that a pregnancy pairing arrangement was broken in error this week. No other pairs offered on the Trade Bill on Tuesday were broken." If the government had lost the customs vote, the number of Tory MPs demanding a confidence vote in May would probably have passed the 48 needed to trigger one.

Smith is lucky the government did not win by just one vote instead of six. In normal times, he may have fallen on his sword, or been sacked. Of course, these are not ordinary times. We have a zombie government that survives not week-to-week but day-to-day. May has already lost her deputy prime minister, home secretary, defence secretary and international development secretary. In recent weeks, she has lost 11 ministers and parliamentary aides who oppose her Brexit strategy, including her foreign secretary and Brexit secretary. She must have had more mini-reshuffles than hot dinners.

So she can ill afford to lose another minister. May must regret moving Gavin Williamson from chief whip to the the Ministry of Defence; he is out of his depth there. Although Williamson liked to model himself on the ruthlessly ambitious Francis Urquhart in TV’s House of Cards, he was more experienced than Smith and so would probably not have broken apparent pairing deals.

Chief whips do not normally speak in the Commons, but that is a convention, not a rule. Smith, who has given conflicting accounts of what happened, should come clean in a statement to MPs before their summer recess starts on Tuesday. He may hope the row blows over during the break. May should tell Smith “never again”, but can she trust him? There will be many more knife-edge Brexit votes this autumn and winter, and they will decide the country's future.