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.

Brighton Pavilion MP Caroline Lucas described the decision as a "victory for parliamentary democracy" and called on labour to change its stance to Article 50 in light of the decision.

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."

Attorney General Jeremy Wright has said the Government is "disappointed" by the Supreme Court ruling but will comply with it.

Ms Lucas, Green Party co-leader, said: “This case is a win for parliamentary democracy, and a blow for those minister who planned to railroad Brexit through without any proper scrutiny.

"The spotlight now falls on MPs – and in particular the Labour Party – to properly scrutinise the Government’s plans and act accordingly.

"That must mean that Labour rethink the support they’ve given to triggering Article 50 prematurely, and instead join those of us who refuse to be pushed into Theresa May’s artificial Brexit timetable.

“It’s astonishing that ministers ever thought it was right to trigger Article 50 without a vote in Parliament - and their battle in the courts really does expose a contempt for the democratic process within the Conservative party.

"I will not be capitulating to the Tories over Brexit – and will vote against prematurely triggering Article 50 in the Spring.

"As the co-leader of a party which stands for environmental, social and economic justice I will not support a Government offering no assurances to EU nationals living in Britain, threatening to turn this country into a tax haven and planning to throw us off the Brexit cliff edge by ending our membership of the Single Market and Customs Union.”