Commons standing orders dusted off to make sense of Nationalist protest

chair. Given his marching orders, Blackford strode purposely from the chamber – but his troops enjoyed the procession, stopping to wave at Labour and Tory MPS.

They cheered and beamed behind their leader in the Central Lobby. No SNP MP has ever looked happier than Mhairi Black marching out of Westminster. Back in the Commons, the stunt was denounced and Labour MPS reclaimed the benches they lost in 2015.

What did it achieve? Beyond the shock and awe, not a lot, but government whips quickly circulated a note to Tory MPS. “We must guard against any procedural ambushes,” it warned.

Fear and uncertainty: the byproduct of the best guerrilla campaigns. Two of the standing orders of the House of Commons were deployed during yesterday’s chaotic PMQS – one by the SNP leader Ian Blackford, and another to throw him out.

Standing order 43 gives the speaker the power to suspend members, not just to leave the Commons chamber, but from “the precincts of the Palace of Westminster”. Failure to comply can lead to arrest, and in previous centuries imprisonment in cells within Big Ben. Despite giving several interviews on College Green (which is technically part of the precincts), Mr Blackford escaped punishment.

He becomes only the third SNP MP to be ejected, after Alex Salmond in 1988 and Jim Sillars in 1989, both barred for five days for “disorderly conduct”. During a Budget debate, Mr Salmond bellowed at Nigel Lawson: “The Budget is an obscenity, the chancellor cannot do this.”

The SNP deployed the last standing order, number 162, which traditionally triggered an immediate vote on sitting in private. The Speaker’s office said yesterday there was “discretion” to delay the request as it fell in the middle of PMQS. Until the late 1990s, an MP could clear the public galleries by shouting “I spy strangers”, and the procedure was used as a way to enforce a quorum – a vote is not valid unless 40 members take part.

In 2001, the Lib Dems surprised the government, stopping ministers from cutting short debate on terrorism legislation. And in 2003, a Labour MP used the device to block a bill to require parliamentary approval of special advisers. The bill’s Tory promoter called it “a piece of jocular parliamentary game playing”. His name? John Bercow.