Anti-Brexit campaigners have failed in an attempt to force Boris Johnson to ask for an extension to article 50 if he is unable to get a Brexit deal through parliament.

Lord Pentland, sitting in the court of session in Edinburgh, rejected their request for a court order instructing the prime minister to seek an extension if he cannot get a deal passed by the Commons this month.

Pentland said he had to take at face value pledges made by the UK government on Friday that Johnson would write the letter seeking an extension on 19 October as required under the so-called Benn act. Pentland said those assurances were unequivocal.

"I approach matters on the basis that it would be destructive of one of the core principles of constitutional propriety and of the mutual trust that is the bedrock of the relationship between the court and the crown for the prime minister or the government to renege on what they have assured the court that the prime minister intends to do," the judge ruled.