Angela Rayner made the most of Boris Johnson’s big mistake over Owen Paterson at PMQs

Angela Rayner is a lucky politician. After she embarrassed herself by calling the Conservatives “scum”, she managed a full if belated apology last week, and this week was able to move on from her misjudgement with one of the most effective attacks on the government since Boris Johnson became prime minister.

The coincidence of an error of judgement on Johnson’s part, and Keir Starmer being forced to isolate after testing positive for coronavirus, handed her an opportunity she didn’t waste. It is not often a prime minister makes a decision as bad as this. The idea that Tory MPs don’t think the rules apply to them had already gained enough purchase among the general public that it should have alarmed No 10. Now Johnson has put it up in lights.

A lot of MPs believe that public opinion is not interested in the details of Commons disciplinary procedures, but I think they are mistaken. The issue is simple. “Paid advocacy is wrong,” as the prime minister said. He went on to say that “this is not the issue in this case” and said that it was about whether an MP has a right of appeal against a finding.

But, as Rayner noted, that looks like trying to change the rules after the event because you don’t like a decision – a decision of an independent commissioner that was endorsed by an independent committee, half of whose members are not MPs. It is no use Johnson protesting that Owen Paterson should be shown “moderation and compassion”. Paterson’s pleas in mitigation – that he thought he was acting in the public interest and his wife has died by suicide – were heard by the independent commissioner and the independent members of the standards committee. To suggest that MPs as a whole – with a whipped Conservative majority – should reach a different conclusion on those facts is the opposite of impartial justice.

This is such a serious mistake on Johnson’s part that we must wonder whether it will contribute to his downfall whenever it comes. It may not be in the same league as Margaret Thatcher’s refusal to amend the poll tax, or Tony Blair’s decision to join the US invasion of Iraq, or David Cameron’s failure to secure a deal that would win the EU referendum, but you don’t have to look far back in history to see a Tory government, already broken backed by its management of the economy and divided over Europe, in the end absolutely flattened by the charge of “sleaze”.

Johnson must know how dangerous this is. “It’s one rule for them and one rule for the rest of us,” said Rayner. That charge did him much needless damage last year after Dominic Cummings’s migration to Durham. This year he steered away from the precipice after he and Rishi Sunak briefly considered declaring themselves part of a pilot scheme that meant the rules on Covid isolation didn’t apply to them.

Rayner played the issue well at Prime Minister’s Questions. Nothing personal about Paterson; just the principle, that if you are a police officer, a teacher or a doctor, “we would expect the independent process to be followed and not changed after the verdict”. In almost the only substantive part of their exchanges, Johnson tried to claim that all the professions she mentioned have a right of appeal (teachers don’t have an automatic right of appeal). He may even have a point, in that an MP’s right of appeal – beyond the two-stage process of the standards commissioner and the committee – is to the House of Commons itself, which is indeed unsatisfactory and has led to today’s unedifying spectacle. But he is proposing to change the rules during one particular case: that is indefensible. Worse than that for the Tory party, it is a public relations disaster.

Rayner had some good lines. “If you keep cheating the public it catches up with you in the end,” she said. She moved on to asking how much taxes would increase on the average household over the next five years (£3,000, the prime minister did not answer), who would pay for the “hidden cut” in day-to-day defence spending (presenting Labour as strong on defence) and suggesting the money for the tax cut for short haul flights should go to veterans’ mental health (Labour, strong on defence and green).

All Johnson could do, apart from accusing her of playing party politics, was to play party politics, in this case rather effectively, driving a wedge between her and her leader: “I don’t want to cause any further dissension in the benches opposite, but I think you’ll agree she has about a gigawatt more energy, Mr Speaker, than her friend.”

After today’s shameful attempt to overturn an independent finding that one of his own MPs broke the rules, he will need to worry that it will take more than divisions in the Labour Party to save him.