Speaking hours before the first face-to-face talks between Boris Johnson and new European Commission president Ursula von der Leyen , he said the Withdrawal Agreement already included protection on key issues like citizens’ rights and Northern Ireland.
“When people say there will be a no deal at the end of 2020, it’s missing the point. The Withdrawal Agreement safeguards many issues that people rightly were concerned about a no-deal exit," he said.
“Things like citizens rights are protected, whether we have a trade deal or not at the end of 2020."
Asked how a trade deal, which normally takes years to complete, could be negotiated and ratified by December, Mr Barclay said the timetable had been agreed by the EU and would not be extended.
However, former German ambassador to the UK Thomas Matussek said the timetable was “extremely ambitious” and amounted to barely six months once the ratification process was included.
Mr Barclay and his opposite number Michel Barnier will join the talks at No 10 between Mrs von der Leyen and the Prime Minister.
The talks will also cover EU-UK co-operation over the crisis in Iran.
Speaking ahead of the visit, Mrs von der Leyen said: “It’s in our mutual interest to build a new partnership that will enable us to defend and strengthen our interests, both from an economic and a security point of view.”
She was also due to deliver a lecture at London School of Economics, which EU sources believed would contain some pointed warnings to the UK that it would find life more difficult outside the EU unless it aligns closely with the 500 million consumer single market.
MPs were today debating the Brexit Bill, which will be passed in time for leaving the EU on January 31.
Opposition MPs were pressing an amendment demanding the Government continues to take in lone child refugees from Europe.