The smart alec reaction at Westminster to the Supreme Court ruling against prorogation is: “Nothing has really changed.” The prime minister dismisses the legal rebuke as wrong. He is still determined to take the UK out of the EU on October 31. He gives a blunt “no” to any suggestion that he might obey the Benn Act’s instruction to seek an extension of membership if a withdrawal agreement has not been reached and approved in the Commons by October 19.

In practice the Brexit endgame has been transformed by the judgment. Parliament is back in business. Johnson does not command a majority there; his opponents do. Unless he can find ways of getting round the Commons or suspending it for significant periods this side of