A former prime minister will testify in the UK's highest court to brand Boris Johnson's suspension of parliament illegal.
Sir John Major is set to give a 20 minute speech in the Supreme Court as judges decide this week whether or not Mr Johnson's parliament shut down until October 14 was unlawful.
The most powerful court in the land today opened a landmark three-day case to hear appeals from two separate challenges in England and Scotland.
Last week judges at Scotland's highest court ruled Mr Johnson's prorogue was motivated by the "improper purpose of stymieing Parliament", and that he misled the Queen to authorise it.
They added: "The Court will accordingly make an Order declaring that the prime minister's advice to HM the Queen and the prorogation which followed thereon was unlawful and is thus null and of no effect."
The government reject that the prorogation was designed to halt attempts to block no-deal, and insist it was routine to bring a fresh legislative programme with a Queen’s Speech.
Number 10 launched an appeal against the Scottish ruling, which will be heard alongside a case by Remain campaigner Gina Miller, supported by Sir John.
Last week High Court Judges in London threw out Ms Miller’s challenge, declaring it a matter for politicians not the judiciary.
Sir John, who was in office between 1992 and 1997, plans to use his experience to "assist" judges in their decision.
Last month he said: "I intend to seek to assist the Court from the perspective of having served in Government as a Minister and Prime Minister, and also in Parliament for many years as a Member of the House of Commons.”
Mr Johnson has said he will "wait and see what the judges say" before making any decision on whether to recall MPs.
Speaking to the BBC, Mr Johnson said he had the "greatest respect for the judiciary," and its independence "is one of the glories of the UK".
"And I think the best thing I can say, having said that, is to wait and see what they say," he said.
Asked again if he would be ready to recall Parliament if that was what the Supreme Court said he ought to do, he said: "I think the best thing I could do is wait and see what the judges say."
