Two weeks ago at Prime Minister’s Questions, the SNP’s Westminster leader, Ian Blackford, drew jeers for welcoming a delegation of Dutch MPs to the public gallery in their own language.

On return to the Netherlands, the fact-finding mission gave its view about how ready the UK was for Brexit.

“The British are only now having the discussion about what kind of Brexit they actually want, a debate that should have been held three years ago, before the referendum,” they reported. “They blame each other and others, which in turn leads to bitter negotiations, with all the risks that entails.”

The Independent Group hold their inaugural meeting on 25 February. Picture: John Stillwell/Getty

As the Commons prepares for its second and probably decisive vote on Theresa May’s Brexit deal, the story feels illustrative of where the UK is, and how it got here. With just three weeks until the UK is scheduled to leave the EU, and nearly three years on from the referendum, it remains unclear when Brexit will happen, if it will take place at all, and whether the UK will leave with a deal, or tumble into an uncertain future without one.

Even if it is agreed, the deal puts off much of the hard negotiating on future security collaboration and trade to a future “transition” phase whose length is equally uncertain.

To clear the path to this point, Brexit has swung a wrecking ball through the delicate precedents and niceties of Britain’s political system and its unwritten constitution. The government suffered the biggest Commons defeat in modern history and was found in contempt of parliament for the first time ever, but carries on. Conservative MPs were told to stop turning up for non-binding votes in the Commons. Constitutional rows between the devolved and UK governments have reached the Supreme Court twice. Thirteen ministers have resigned over Brexit, and collective responsibility is a distant memory. Ministers who might have expected the sack in previous years remain in cabinet. Parliamentarians and judges have been denounced as traitors, and police now protect MPs from protesters outside Westminster. The government fears putting crucial Brexit legislation in front of MPs, while domestic issues are neglected. Post-Brexit regulations are being pushed through as giant pieces of secondary legislation, without the full scrutiny of the Commons. February recess was cancelled, but with nothing to debate in the Commons chamber, on one day the House rose after a four-hour session at half past three in the afternoon.

Most of all, after 45 years of partnership and 24 months negotiating its divorce, the UK seems unable to communicate with Europe – and attempts to do so are dismissed.

Theresa May addresses the Commons on the day of her historic defeat, 15 January. Picture: PA

“At any time when I was in the House of Commons, any one of these developments would have been unthinkable,” says Lord Wallace of Tankerness, who has served in parliament and cabinet in London and Edinburgh. “If they had happened during the coalition years, commentators would have dismissed the coalition government as weak and unstable. But constitutional aberrations are now becoming routine.”

“I didn’t vote in the referendum. I disapprove of referendums,” says former chancellor Ken Clarke, the veteran Europhile Tory MP whose seniority makes him Father of the House of Commons. “Mussolini used them brilliantly. He was able to shut up Italian politicians, and neutralise the Italian parliament, for God’s sake – that was quite an achievement. Unfortunately, because it’s Europe, one referendum has reduced Westminster to chaos.”

Few would argue that Brexit has broken Westminster. So how did it happen?

From the beginning, time hasn’t been kind to the UK on Brexit. The two-year Article 50 period has squeezed Britain’s negotiators. But the government hasn’t always put the time it had to the best use.

Stephen Gethins, the SNP’s Europe spokesman and previously an adviser to both nationalist first ministers, says that if the UK made its decision on Brexit without all the facts, it’s partly because there was never time to get them across.

After being elected as an MP in 2015, the EU Referendum Bill was one of the first pieces of legislation he worked on – but before the vote on Europe, there were English local elections, a London mayoral vote, and elections to the Scottish Parliament. “Politicians are like football managers – they only think about one game at a time,” says Gethins. “The EU referendum campaign didn’t really get started until six weeks before the vote. There was very little time for either side to actually hammer out what Brexit meant.”

“No-one thought of the Irish border,” says Clarke. “Had anyone raised the Irish border during the referendum campaign, I think a lot of the leading participants on both sides would have had to run away and look it up, and remind themselves.”

Parliament’s struggles to make a concept as poorly understood as Brexit a reality has helped create the toxic atmosphere of today’s politics, Clarke believes. It’s easy to call someone a traitor to an idea no-one can define. “With the increasing complications and complexities of modern life, it’s easier to listen to politicians with simple solutions, identify scapegoats – foreigners, or Brussels – and simply denounce in abusive terms anybody who disagrees with you.

“It’s happening in every Western democracy – the Trump phenomenon, Brexit, and the yellow jackets are all very similar. They’re basically the same angry public protest.”

Having inherited the decision to leave the EU, May struggled to come to terms with the magnitude of the task. Nine months on from the referendum, to ease pressure from Brexiteers, she triggered Article 50 and put herself under pressure from the clock – while trading away the UK’s only real leverage in the process.

“Theresa May stood up in her 2016 party conference speech and said it would be a mistake for us to trigger Article 50 without knowing where we want to go,” says Joseph Owen, who monitors the strain Brexit puts on the Westminster machine as an associate director at the Institute for Government think tank. “But that’s precisely what we did.

“If you look back at that speech, for what it says about the Brexit process, if you put aside the setting of the red lines… there are some quite sensible things in there that make you think – if only we had done it like this.”

Even Brexiteers believe the clock was started too early. Scotland on Sunday spoke to a Brexit-supporting former minister who declined to be named. Of the “many mistakes” made over the past three years, they put triggering Article 50 “too soon” at the top of the list.

“The government made the right decision to consult widely across the economy and to make an assessment of what our priorities were in the negotiations,” the ex-minister said. “It should have spent longer doing that.”

Ironically, the general election called less than three weeks later was ordered in part out of fear of the government’s narrow majority. Even if the campaign hadn’t been a disaster, it put Brexit on hold.

“Obviously it was damaging in the respect that the government lost its overall majority, but it also lost an awful lot of valuable time and momentum,” the Brexiteer source said.

Less time for negotiation also meant less time for preparation, some of which was avoided for political reasons. “The government started communicating about ‘no deal’ in September last year,” says the IfG’s Owen.

“That’s six months out for a massive change. The UK Government usually gives businesses years to adapt to changes smaller than this.

“Politically, ministers didn’t want to say, after having just secured a transition agreement, here are all the nightmare things that could still happen.”

Losing her majority meant May’s government owed its existence to MPs from other parties. The £1.5bn deal with the Democratic Unionist Party kept the Conservatives in power, but Downing Street had no plan to replace votes lost through inevitable rebellions by pro-EU Tories. The first meetings between the government and opposition parties took place in January, and a £1bn financial offer for Leave-voting Labour areas was only cobbled together in the past fortnight.

“Holyrood does minority government well,” says Gethins. “At Westminster, minority government is a crisis.” As a special adviser in the first SNP minority administration, he learned the importance of forging working relationships with political rivals.

“My job was to talk to other parties and maintain relationships with the opposition,” he explains. “We had a full term and by the 2011 election, we had passed four budgets, working across all the parties. At Westminster, if something is cross-party, it toxifies it in Downing Street’s eyes.”

Cross-party support for sports minister Tracey Crouch over regulation of fixed-odds betting terminals, and for Scotland Office parliamentary secretary Alberto Costa in his campaign for a guarantee for EU citizens, made it tougher for the government to respond – until after they had resigned. “It was completely unnecessary,” says Gethins.

Indeed, most of the cross-party work on Brexit has happened in spite of the government. The SNP, Liberal Democrats, Plaid Cymru and the Greens formed a committee to call for a soft Brexit and a second EU referendum. Downing Street invited a cross-party group of Remain-supporting MPs for a briefing in January, but rather than convincing them to back the deal, it drove them away: among the delegation were members of the soon-to-be-formed Independent Group, including Labour MP Chuka Umunna and Tory Anna Soubry.

With the help of Whatsapp, pro-EU MPs have organised themselves: Scotland on Sunday was told about one group of around 30 MPs whose members include Lib Dems Alistair Carmichael and Jo Swinson, Green Party MP Caroline Lucas and the Independent Group’s Chris Leslie. Along with the Brexiteer European Research Group, these informal alliances have helped inflict 13 Brexit defeats on the government in 18 months.

It’s in stark contrast to Alex Salmond’s offer for opposition party leaders to join the negotiating team if Scotland voted for independence, or Nicola Sturgeon’s creation of a council of advisers on Europe that includes figures from other parties, Gethins argues.

Losing her majority in the Commons coincided with May losing control of her own cabinet. Clarke was in government the last time Eurosceptics made life impossible for a Conservative prime minister. Recalling debate around the treaty that founded the EU, he says: “Maastricht was just a tea party compared with the present crisis over EU withdrawal, which has for the time being made the ordinary rules about collective responsibility in cabinet and the two big parties almost redundant.”

As a no-deal Brexit has become more likely, Remainers in the cabinet have staged their own protests, winning a vote on extending Article 50 by threatening to resign. “[The Prime Minister] should say, ‘well go ahead and resign,’” the Brexiteer ex-minister says. “There are plenty more people who could fill your places. These are people who will vote against her anyway. When you get ministers of the political weight of [business minister] Richard Harrington trying to tweak her tail, then you know you’ve got big problems.”

The breakdown in party discipline has been politically embarrassing, but on a practical level, behind the scenes of Whitehall the chaos has made a difficult task even harder for civil servants. “All of a sudden you had different ministers on the airways every week spelling out their own visions and slightly contradictory things,” says Owen of the period since the election. “I don’t think we’ve ever really recovered from that moment.”

No government policy since the war has placed such great demands on so many departments at the same time. The level of coordination needed is huge, but it has been stifled by conflicting agendas and an insistence on secrecy and control from Downing Street.

“Take the border,” Owen says. “It involves something like 20-odd government departments and agencies, and more than ten ministers have a say.” Philip Hammond at the Treasury handles the trade tariffs, Chris Grayling at Transport the logistics, Michael Gove at Defra is in charge of regulations, and Greg Clark at BEIS [Business, Energy and Industrial Strategy] is responsible for supply chains. “You’ve got a real mix of political personalities who are driving their departments in different directions in terms of Brexit priorities,” Owen says. “That’s where the point about secrecy comes in.”

Documents as essential as the planning assumptions for Brexit, setting out what the government expects and what each department should prepare for, were massively over-classified, IfG research found.

“It meant that you had to go on to special computer terminals or go and access hard copies in the permanent secretary’s office if you wanted to see these documents,” says Owen.

“You’re talking about billions of pounds worth of plans, hundreds and hundreds of them, relying on documents of which there are at most 20 or 30 copies circulating in Whitehall, and there are only certain rooms you can access  them in.”

The situation is reminiscent of how the Prime Minister wanted her own office run, particularly before the general election, by her chiefs of staff Fiona Hill and Nick Timothy. In times that call for flexibility, the person chosen by Tory MPs – all the other leadership candidates were eliminated or withdrew – has, until recently, demanded total control.

One source tells of a Brexit-related call with a rival political leader where May appeared to read a written statement down the phone. “Social skills are basic requirement of being a politician,” the source says. “She doesn’t do any of the small talk to warm things up.”

The government’s political relationships in Brussels have come under even greater strain than those in London. Pro-EU critics blame the failure to communicate on a lack of experience among the vast majority of MPs of working in and with Europe. A source tells of Brussels-based civil servants having to explain the difference between the European Commission and the European Council to Westminster parliamentarians.

At an even more fundamental level, many top European politicians speak English; as a documentary on Boris Johnson’s time in the Foreign Office showed, senior British figures often can’t communicate in the tongue of their opposite numbers. Europe follows our news broadcasts and reads our newspapers and we can’t read theirs.

David Martin, the veteran Scottish Labour MEP, who is one of the UK’s longest-serving parliamentarians, says that from Brussels, it looked like the UK government believed the EU “would be willing to make all sorts of concessions to the UK that were never on the cards”.

“The illusion that the UK was this great power that the EU would bow down to was surprisingly prevalent in certain quarters,” he says. “Linked to that is the idea that Europe always starts tough in negotiations and eventually gives in. It’s a myth that is still being perpetrated.”

Some in the government hope there can be a third Brexit vote and more negotiations even if MPs reject the deal again this week, but Martin sees limited room for manoeuvre.

“Europe is very, very adept and used to negotiating across parties and across interests,” he says. “It needs to find consensus on issues which, from a British point of view, is seen as a weakness. And once they reach a consensus, it’s a pretty firm consensus, because, by definition, to reach it people have had to make concessions and it’s very difficult to go back and make further concessions.

“When Europe got 27 member states around the table, the European Parliament and the Commission and [European’s Chief Negotiator Michel] Barnier and everybody else… it actually became quite difficult for it to move too far one way or the other. In the British adversarial system, Britain thought: ‘We have a line, they have a line, we start clashing and fighting, and then the changes come.’ From Europe’s point of view, the position was set before they even sat down to talk.”

As difficult as the journey to this week’s vote has been, Brexiteers are content with the outcome. “I’m not unhappy at all with where we are at the moment, because it looks very much as if we will be heading out on 29 March without this awful deal,” says the ex-minister.

“We’re living in such historically unusual times, I don’t think you can project anything as to the future out of it. We have to just acknowledge that this is the most extraordinary parliament that there has ever been.”

Others are more concerned about the long-term impact from three years of upheaval. Lord Wallace likens it to the “normalisation” of the worst behaviour of President Trump. “Revelations or incidents which would once have caused outrage become accepted, because they become routine,” he warns. “In a country with no written constitution, and where precedent matters, I fear we may be in danger of normalising the unprecedented constitutional outrages being perpetrated by the present government.

“The irony is that this marginalisation of parliament has been done in pursuit of ‘taking back control’.”

POSSIBLE SCENARIOS

• Tuesday: After a full day of debate, MPs will vote on the deal Theresa May has negotiated with the EU. A specific time for the vote has not been released.

• Wednesday: If the deal is voted down, as expected, MPs have been promised a vote on whether the UK should leave without a deal or not. This is expected to take place on Wednesday.

• Thursday: If ‘no deal’ is rejected by a majority of MPs they may be offered a vote on whether to request a delay to Brexit.

• Friday, 29 March: Britain leaves the EU with or without a deal unless a delay has been agreed.

IN NUMBERS

230 - Number of votes by which Theresa May’s Brexit deal was defeated –the largest government defeat in modern parliamentary history

13 - ministers have resigned over Brexit since the 2017 general election

6 - bills needed to prepare for a no-deal Brexit that have yet to be passed: the Trade Bill, the Agriculture Bill, the Fisheries Bill, the Immigration Bill, the Healthcare Bill, and the Financial Services Bill

600 - Number of statutory instruments needed to prepare for Brexit day. 80% presented so far

13 - government defeats in the Commons on Brexit-related business

Insight: Politics torn apart by Brexit bid to take control