THE Government has lost its historic battle in the Supreme Court over Brexit.

The highest court in the land rejected an appeal by ministers against a High Court judgment blocking their decision to begin Britain's exit from the European Union without Parliament having a say.

Supreme Court justices ruled, by a majority of eight to three, that Prime Minister Theresa May cannot lawfully bypass MPs and peers by using the royal prerogative to trigger Article 50 of the Lisbon Treaty and start the two-year process of negotiating the UK's divorce from its EU partners.

The ruling is a blow to Mrs May, who has repeatedly said she intends to trigger Article 50 by the end of March following the clear majority in favour of Brexit in the June 2016 referendum.

It was won by a wide-ranging group of anti-Article 50 campaigners led by investment manager Gina Miller, 51, and hairdresser Deir Dos Santos.

Supreme Court President Lord Neuberger said: "By a majority of eight to three, the Supreme Court today rules that the Government cannot trigger Article 50 without an Act of Parliament authorising it to do so."

Although the Government lost the challenge, the justices unanimously ruled that there was need to consult with the devolved powers in Scotland, Wales and Northern Ireland.

On the steps of the court, Attorney General Jeremy Wright said the Government was "disappointed" by the Supreme Court ruling but will comply with it.

In one of the most important constitutional cases in recent British legal history, three High Court judges ruled in November that ministers lacked authority to invoke Article 50 without parliamentary approval.

The Lord Chief Justice, Lord Thomas, sitting with two other senior judges, upheld the "powerful constitutional principle" that Crown prerogative powers could not be used "to alter the law of the land".

Last December, Brexit Secretary David Davis led the Government's attempt to overturn the ruling in a four-day hearing before a record 11 Supreme Court justices.

A team of Government QCs argued the High Court was wrong in law and it was "a fundamental pillar" of the constitution that prerogative powers could be used to make and unmake treaties with foreign governments and not an affront to Parliamentary sovereignty.

Glostays, Gloucestershire-wide campaign group to stay in the EU, welcomed today's judgement.

Chair of Glostays, Matt Lewis-Garner said "It is a sad irony that Theresa May has called for Remainers and Leavers to unite and support the Brexit negotiations, but the only thing that Remainers and Leavers can be united over is the ruling of the Supreme Court that Parliament is, and always has been sovereign, and that Theresa May cannot act like a dictator.

"This is exactly what Leave voters were voting for, and exactly what Remainers knew we already had; the sovereignty of the UK Parliament."

Secretary of Glostays, and legal counsel, Lindsay Hamilton-Reid added: "This is not about stopping Brexit, this is about the rule of law, the sovereignty of Parliament and ensuring that the Prime Minister cannot act unilaterally against the wishes of our elected Parliament. This is a good day for British democracy."

Parliament is expected to vote to trigger Article 50 at the end of March after scrutinising the Government's proposals.