HOW does democracy end? The Cambridge professor and broadcaster David Runciman recently published a book asking precisely that question.

He would certainly recognise the chaotic scenes in Westminster as evidence that our system of parliamentary democracy, if not dead, is at least pretty unhealthy. There’s more than a whiff of Weimar in the parliamentary deadlock over Brexit.

Scuffles at the Speaker’s chair; MPs holding placards in the chamber; chanting “shame on you”; singing the Red Flag and Scots Wha Hae into the small hours – it was a rammy, an emotionally-charged demonstration that the conventions of Parliament no longer work.

Of course, Boris Johnson has brought this on himself by wrecking convention first. There was no legitimate reason for suspending Parliament five weeks early. It was a weak Government trying to assert authority, like a parent threatening to send a teenager to bed early – and failing.

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It may not have been a “coup”, but the prorogation was pointless provocation. Parliament was about to go into recess anyway for the party conference season. (Indeed, anyone who was hoping for a holiday from politics will be unpleasantly surprised when the Liberal Democrats launch their beano in Bournemouth this weekend. Thereafter it will be wall-to-wall Brexit-on-sea.)

Westminster functions through an understanding that both government and opposition are capable of co-operating in the national interest. MPs address each other as Honourable Members, not by name or political party. Parliament works only when both sides recognise a series of gentlemen’s agreements, or precedents, which are not written down anywhere.

Well, no one gives a monkeys for protocol any longer, and gentlemen no longer exist. Even the Speaker lost his cool, barking that he didn’t give a “flying flamingo” what MPs thought. He condemned Mr Johnson’s prorogation as an act of “executive fiat”, which sounds like an upmarket Italian car but is Parliament-speak for “elective dictatorship”.

Supporters of remaining in the EU (of whom I am one) have been celebrating these rowdy expressions of parliamentary democracy, and holding Mr Johnson hostage to prevent no deal. I support the objective. But there is a problem when precedents are abandoned chaotically on key issues like disclosure, prerogative powers, dissolution of Parliament and control of the legislative programme. The old rules clearly aren’t working, but we don’t know what the new ones are yet.

Jeremy Corbyn may not be cheering so loudly when he leads a minority government – possibly in only a few weeks’ time – and finds that he can’t get ambitious reforms, like nationalisation, through an unco-operative Parliament. Left-wing governments have most to fear from parliamentary obstructionism. Controversial reforms like the National Health Service might never have happened had the post-war Labour government not had control of the legislative programme.

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How will Mr Corbyn feel when he finds that he can no longer use confidence motions to enforce party discipline against his Blairite rebels? When his private conversations with trade union leaders are published in the Daily Mail? The SNP leader, Nicola Sturgeon, insists that most government advice should be confidential. How will she feel if she strikes a discreet deal with a Labour government over a referendum which is blocked by a rebellion of Labour Unionists crying treason?

Perhaps the most symbolic moment in parliament’s night of shame was the barracking of Black Rod. This poker-faced ceremonial figure is supposed to summon MPs to the Lords to hear the closing of Parliament intoned in Norman French. Only this time, when she summoned the Speaker and MPs, she was met with loud cries of No!

The absurdist protocols of Parliament – the men in tights – largely date from the Victorian age. They are an attempt to turn our constitutional monarchy into a form of theatre, a pageant, to remind people who is in charge. It is not the Queen of course who prorogues Parliament, but the Government in her name. Black-balling Black Rod was a symbolic expression of MPs’ refusal to recognise the convention that governments have the right to dissolve parliament.

Yet this Government has a majority of minus 45 and counting. Mr Johnson has been defeated six times in the space of a week. And not just on any old legislation: the Government has been defeated twice on its attempt to stand down and hold an General Election. The Prime Minister is under house arrest in Downing Street, unable to leave office and unable to get bills through Parliament.

The prorogation, and Mr Johnson’s sacking of the 21 Tory rebels, united MPs behind their own unconstitutional action: seizing control of parliamentary business in order to pass a law trying to force the PM ask for an extension of British membership of the European Union. I say “try” because it’s not yet clear whether Parliament has the powers to tie a Prime Minister’s hands in negotiations with foreign governments.

The partisan Speaker, John Bercow, has abandoned precedent repeatedly. He allowed MPs to overturn the standing order that only the Government may propose legislation. This looks like a long-overdue recognition of Parliament’s sovereign right to rule. But in the Westminster system, governments make the laws and Parliament holds the Government to account. At least, that’s how it is in the parliamentary bible, Erskine May.

We don’t elect a president, with their own constitutional powers. Instead we have what is called The Crown in Parliament, a phoney head of state. This works on the principle that if the PM can’t get their bills through the Commons the government must fall. But we have a Government that has fallen, but cannot die. It is a zombie.

We also have a Parliament of the living dead. MPs have voted against every Brexit option – No Deal, Norway, Withdrawal Agreement, Customs Union, referendum, revocation – but cannot come up with a policy they do support. They demand an extension, but can’t agree on what it is for, or how long. They are not willing or able to govern, yet they refuse to remove Mr Johnson’s Government.

Government by opposition is an oxymoron. Democracy, as Professor Runciman argues, doesn’t end with jackboots and the Reichstag fire. We aren’t under threat from fascism, but from the slow extinction of democracy in a parliamentary system that no longer works.