As the vote on Theresa May's Brexit deal approached, the atmosphere in the House of Commons was at once anxious and flat, as MPs considered the inevitable result and its unpredictable consequences.
Summing up the debate for the opposition, Labour's shadow Brexit secretary Keir Starmer said the mood had been "lively at times but also sombre".
A few minutes earlier, Conservative MP Steve Double spoke for many of his colleagues. "Here we are 20 minutes before the vote, and I don't know how to vote," he said, before going on to back Mrs May's deal.
Some of Mr Double’s fellow Brexiteers also changed their minds and voted with the government but not enough to prevent the deal being rejected by 391 votes to 242, a majority of 149 votes.
The day began with almost all the front pages celebrating the prime minister's success in sealing the deal in Strasbourg at the 11th hour. Both the DUP and Conservative Brexiteers were cautious, keeping open the possibility of voting either way as they waited for attorney general Geoffrey Cox to publish his legal advice.
When he did so shortly after 11am, the impact was explosive, tearing apart within minutes Mrs May’s hopes of securing a majority for her deal. In a three-page letter to the prime minister, Mr Cox said the legally binding assurances she had won from the European Union reduced the risk that Britain could be trapped in the backstop indefinitely if that situation had been brought about by bad faith on part of the EU.
"However, the legal risk remains unchanged that if through no such demonstrable failure of either party, but simply because of intractable differences, that situation does arise, the United Kingdom would have, at least while the fundamental circumstances remained the same, no internationally lawful means of exiting the protocol's arrangements, save by agreement," he said.
After weeks of negotiations with the EU aimed at securing changes that would allow the attorney general to change his legal advice, he was declaring that on the central issue of concern surrounding the backstop, nothing had changed. Within minutes, Conservative Brexiteers were popping up to say they could not vote for the prime minister’s deal and within two hours, the DUP followed suit.
"We already know what the Irish Government and others see as the ultimate destination for Northern Ireland – the backstop is the bottom line. From what the attorney general is saying today, provided there is no bad faith, the fact is that Northern Ireland and the rest of the United Kingdom could be trapped if the EU does not agree with the United Kingdom to a superseding agreement," DUP deputy leader Nigel Dodds said in the House of Commons.
By the time Mrs May opened the debate at 2pm, the "star chamber" of lawyers advising the Brexiteer European Research Group (ERG) had also rejected the deal. She looked up at her husband Philip in the gallery opposite as she got to her feet and as soon as she spoke it was clear her voice was almost gone.
“You should hear Jean-Claude Juncker’s voice as a result of our conversation,” she said.
She made the case for the deal and set out in detail the changes she had secured in negotiations with the EU. But her central message was that MPs had a responsibility to deliver on the 2016 referendum result and to put democracy before party or faction.
When she returned to the dispatch box a few hours later after her deal was voted down, the prime minister told MPs they would vote on Wednesday on whether to leave the EU without a deal. If they rejected a no-deal Brexit they would vote on Thursday on whether to seek an extension of the article 50 deadline.
“But let me be clear. Voting against leaving without a deal and for an extension does not solve the problems we face. The EU will want to know what use we mean to make of such an extension. This House will have to answer that question,” she said.
“Does it wish to revoke article 50? Does it want to hold a second referendum? Or does it want to leave with a deal but not this deal? These are unenviable choices, but thanks to the decision the House has made this evening they must now be faced.”