Theresa May’s statement in Downing Street on Wednesday evening was shocking. Shocking in its level of denial, in its lack of humility and in its complete and utter lack of self-awareness. And shocking too in its complete refusal to take any personal responsibility for the fiasco which Brexit has become.

The prime minister should have at least acknowledged that she bears a huge share of the blame for the utter shambles which is now unfolding and which has, perhaps permanently, shredded Britain’s reputation for sensible, level-headed diplomacy and statecraft.

The PM compounded her performance on Wednesday with what followed in Brussels the next night. One aide to another EU leader described her performance, in a 90-minute address to the other 27 heads of government, as “awful, dreadful – evasive even by her standards”, adding “she didn’t have a plan so they [the other leaders] needed to come up with one for her”.

There can surely be no greater demonstration of the ignominy into which the UK has now sunk under Theresa May’s premiership than the fact that she was then asked to leave the group dinner and made to stay in a separate room for several hours while the other leaders came up with a plan to save Britain from the cliff edge of no deal.

I disagree profoundly with Brexit – that should come as no surprise to anyone given I have been entirely consistent on the issue, before and ever since the referendum almost three years ago.

Britain before Brexit: Scotland Show all 11 1 /11 Britain before Brexit: Scotland Britain before Brexit: Scotland Edinburgh A yellow grit box on the Royal Mile, now containing blankets. One set of contents has been replaced by another, but both are used to make the cold weather less dangerous Richard Morgan/The Independent Britain before Brexit: Scotland Glasgow Students hand feed pigeons, taking time out to feed the birds. And like the lady from Mary Poppins, they too seem proud that they’ve paid the animals attention, happily surrounded by their hunger Richard Morgan/The Independent Britain before Brexit: Scotland Aberdeen A colour-coded stereotype on Union Street, complimenting double yellow lines Richard Morgan/The Independent Britain before Brexit: Scotland Glasgow Two images of man across time: one majestic and colossal; the other distracted and unremarkable. Both are burdened, it seems Richard Morgan/The Independent Britain before Brexit: Scotland Dundee A view of the £80m V&A museum, built on the bank of the River Tay. It’s a controversial addition to the city, providing art and culture and tourism, but not social infrastructure Richard Morgan/The Independent Britain before Brexit: Scotland Inverness The facade of a ‘conspiracy shop’, existing not to make money, but to awaken people from the web of lies in which we supposedly live, to shatter the illusion of reality, to tell the truth Richard Morgan/The Independent Britain before Brexit: Scotland Aberdeen An anonymous act of political expression in modern Britain, adding to the mix, becoming part of the everyday experience of waiting for the green light Richard Morgan/The Independent Britain before Brexit: Scotland Edinburgh Edinburgh’s skyline, overgrown by the skeletal branches of a wintry tree, in which a thrown traffic cone sits entangled and trapped Richard Morgan/The Independent Britain before Brexit: Scotland Glasgow American Christians take it in turns to preach on Buchanan Street. They talk of sin and vulgarity and death and power. It’s an intriguing performance, one framed and mocked by the sex-selling adverts behind Richard Morgan/The Independent Britain before Brexit: Scotland Dundee A Polish football hooligan sticker re-frames the view of the city from the Dundee Law, bringing a foreign presence to the frame, a new look created by the movement of people Richard Morgan/The Independent Britain before Brexit: Scotland Edinburgh Vegan protesters write their ethics on the pavement in chalk, trying to catch the eye of head-down city strollers. Their political graffiti washes away in the night rain Richard Morgan/The Independent

But while I oppose the UK’s departure from the European Union, there was nothing inevitable about the low farce into which Brexit has now descended.

And again, it is Theresa May who bears principal responsibility for that. She could have reached out and sought the broadest possible base on which to build support. That would have involved compromise, but would also have stood the greatest chance of success.

Instead, she has insisted from the start on her immovable red lines which have boxed her in. She then delayed the first vote on her deal in an attempt to run down the clock, and then failed to change course despite two catastrophic parliamentary defeats of her deal.

The speech in No 10 on Wednesday evening was appallingly misjudged in the way it sought to turn people against parliament, and indeed against parliamentarians. In fact, all it seems to have succeeded in doing is in making it even less likely that her deal will get through the Commons if and when she decides to bring it back again for one more go.

There is evidence that MPs who may have been wavering and thinking of backing her proposals are now determined not to, so angered are they by the PM’s hectoring rhetoric and tone. And her arrogant assumption that “the people” share her view cuts to the core of her misjudgement and mishandling of Brexit. She has made no attempt to acknowledge – far less reach out to – the almost half of voters who cast their ballot against Brexit in 2016.

But it now appears that we have at least a chance of avoiding the worst outcome. The deal in Brussels gives the UK an extra two weeks to avoid a no-deal Brexit.

That means it is essential that parliament now takes control away from the PM and uses the extra time it has been given to chart a way forward. SNP MPs will be part of that process and our preference is to secure a longer extension to the Article 50 process to allow time to put the issue back to voters.

Saturday’s march in London, which I plan to attend, will be a huge, visible demonstration of public opposition to the Tories’ mishandling of Brexit. It will follow the astonishing response to the petition to parliament calling for a revocation of Article 50 – something that is in the government’s gift – which had amassed more than 3 million signatures by lunchtime on Friday.