The Supreme Court ruling on Brexit handed down on Tuesday morning could prove to be "a matter of life or death" for five million people across Europe, according to a representative for expatriates.

John Shaw, from the campaign group Fair Deal For Expats, said he was "delighted and relieved" by the judgement, which blocks Theresa May from triggering the process of leaving the EU without first getting Parliament's approval.

Mr Shaw said the Government had been treating the two million British expats in Europe, as well as the three million EU citizens in the UK, as "bargaining chips", and welcomed giving MPs a role over the triggering of Article 50.

Campaigners for the rights of expats, the majority of whom were barred from voting in the referendum, have been involved in the Brexit court case from its onset.

Many British expats living in Europe depend on Britain's membership of the EU for basic needs such as healthcare, the right to work and their children's education.

"Everything people in Britain take for granted in their daily lives, rests for us on our being EU citizens," Mr Shaw said.

"Proper parliamentary scrutiny now offers the best chance for our circumstances to be considered in the lead-up to the Brexit negotiations."

Mr Shaw, who lives in Lauzon in France, said he was suffering from cancer and cited a friend who had lived an extra "four or five years" as a result of French healthcare, paid for under EU rules.

"So it is a matter of life or death," he said. "Together with three million nationals of other European countries who live here, we are the people who will be most profoundly affected by all of this.

"This is the human side of Brexit. We would urge the Government not to use us as bargaining chips. We will be calling on the Government and the European Commission to ensure hard guarantees are put in place about what the future holds for such a large number of ordinary people. We ask that governments across the EU do the same."

Handing down the Supreme Court judges' ruling, which went against the Government by a majority of eight to three, Lord Neuberger said the process of Brexit would change British law and take away legal rights currently enjoyed by British citizens.

Supreme Court Brexit Challenge Show all 13 1 /13 Supreme Court Brexit Challenge Supreme Court Brexit Challenge People wait to enter the public gallery outside the Supreme Court ahead of the challenge against a court ruling that Theresa May's government requires parliamentary approval to start the process of leaving the European Union, in Parliament Square, central London Reuters Supreme Court Brexit Challenge Gina Miller, co-founder of investment fund SCM Private arrives at the Supreme court in London on the first day of a four-day hearing Getty Supreme Court Brexit Challenge A man waves the EU flag in front of the Supreme Court Getty Supreme Court Brexit Challenge Satirical artist Kaya Mar poses with two of his paintings in front of the Supreme Court Getty Supreme Court Brexit Challenge Pro-Europe protestors dressed as Supreme Court Justices stand outside the Supreme Court ahead of the first day of a hearing into whether Parliament's consent is required before the Brexit process can begin. The eleven Supreme Court Justices will hear the government's appeal, following the High Court's recent decision that only Parliament can trigger Article 50 Getty Supreme Court Brexit Challenge The eleven Supreme Court Justices will hear the government's appeal, following the High Court's recent decision that only Parliament can trigger Article 50 Getty Supreme Court Brexit Challenge Businesswoman Gina Miller arrives at the Supreme Court ahead of the first day of a hearing into whether Parliament's consent is required before the Brexit process can begin Getty Supreme Court Brexit Challenge Attorney General Jeremy Wright arrives at the Supreme Court in London EPA Supreme Court Brexit Challenge Protesters outside the Supreme Court in London, where the Government is appealing against a ruling that the Prime Minister must seek MPs' approval to trigger the process of taking Britain out of the European Union PA wire Supreme Court Brexit Challenge A protesters wearing a judge's wigs and robes stands outside the Supreme Court ahead of the challenge against a court ruling that Theresa May's government requires parliamentary approval to start the process of leaving the European Union, in Parliament Square, central London Reuters Supreme Court Brexit Challenge A protester holds up a placard outside the Supreme Court ahead of the challenge against a court ruling that Theresa May's government requires parliamentary approval to start the process of leaving the European Union, in Parliament Square, central London Reuters Supreme Court Brexit Challenge Pro-Europe protestors dressed as Supreme Court Justices stand outside the Supreme Court Getty Supreme Court Brexit Challenge A man waiting to enter the public gallery waves a European Union flag outside the Supreme Court ahead of the challenge against a court ruling that Theresa May's government requires parliamentary approval to start the process of leaving the European Union, in Parliament Square, central London Reuters

"The UK’s constitutional arrangements require such changes be clearly authorised by Parliament," he said.

Lord Neuberger said the judgement was not about the referendum result or a comment on the merits of leaving or staying in the EU.

"The referendum is of great political significance, but the Act of Parliament authorising it did not say what would happen afterwards," Lord Neuberger said, meaning any action taken now must be in keeping with the UK’s constitution.

UK government does not need Scotland and Northern Ireland's permission to trigger Article 50

Speaking outside the court, the Attorney General Jeremy Wright said the Government was "disappointed in the outcome".

He said that Britons were "fortunate enough to live in a country where everyone... even the Government... is subject to the rule of law", adding that the Government would comply with today's judgement.

The verdict will come as a considerable blow to Ms May, amid growing criticism that her plans for EU withdrawal are chaotic.

The Prime Minister will now have to give Parliament the chance to vote on whether to trigger Article 50, the mechanism by which EU withdrawal can formally begin.

It is unclear what will happen legally if MPs vote against the bill which Ms May is now required to bring forward, as much of the constitutional law related to Brexit remains as yet untested, although Jeremy Corbyn has "asked" his MPs not to vote to obstruct it.