Mr Barnier said: “I worked every day, every day sometimes every night during these four years thinking about this point, and this clear danger of peace in Ireland in case of any trouble for the Good Friday/ Belfast agreement.
“And we take a lot of time to work the British environment with Theresa May one time, two times, three times.
“We found a solution which Theresa May, and finally we found an agreement with Boris Johnson. Not against him. Without him, but with him.
“And once again, every word, every sentence was negotiated.”
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Emily Maitlis asked: “They understood exactly what the protocol meant?”
Mr Barnier replied: “Yes. There is no surprise. There was no surprise.”
The BBC Newsnight presenter then asked: “But recognise that it’s not working. The protocol is not working.”
Mr Barnier said: “ We need to respect the signature.”
She then asked again: “But if Jeffrey Donaldson says it’s the end of power-sharing.
“If that’s not going to create peace, does the EU not have to be more flexible?”
Mr Barnier said in response: “The Vice-President of the Commission, Maros Sefcovic said several times, including a few days ago, ‘we are ready to find a practical and operational solution in the framework of the protocol, not for renegotiating’.
“Because this protocol has been negotiated by serious people on both sides, very serious people.
“And Boris Johnson is a serious prime minister. So we negotiated with his team, with himself.
“He knew exactly what he signed.”
Ms Maitlis asked: “Don’t you think the protocol will just be dropped eventually? Quietly dropped?”
Mr Barnier replied: “It cannot be possible to drop this protocol because it’s the only way to find a solution for all the problems created by Brexit.
“What creates problems in Ireland is Brexit, nothing else.”