For the second time in a week, conservative MPs have fallen foul of hitherto obscure rules.
Hot on the heels of Matt Hancock's reversal of fortunes with his UN job comes news that Boris Johnson is understood to be considering his position after receiving a letter from a Commons select committee. The letter brought to his attention a recently unearthed 250-year-old parliamentary rule precluding him from carrying out the role of Prime Minister.
The committee's chair told Andrew Marr. 'It's all very unfortunate for Boris, but the little-known rule, drafted in 1774 and never suspended, clearly states that incompetents, philandering chumps and feckless dolts cannot be considered for the job.
'As Mr Johnson passes the litmus test for all three, we have asked him to step down immediately. Therefore, under the rule, he is unfit to hold the office of First Lord of the Treasury.'
However, it seems the PM is not ready to walk just yet. A spokesman for No. 10 said: 'Look, Boris has handed this over to Carrie to sort out as he can't be diverted from his purpose at such a critical time in the nation's welfare.
'To those ends alone, this week, he is already booked for five gala dinners and a Tory fundraiser. All of this before he's then off on a gruelling two-week fact-finding mission in Mustique. Great Britain simply cannot afford to lose his inestimable insight and knowhow in these vital affairs of state.'
