There’s a very old saying that suggests anyone who chooses to represent themselves in court has a fool for a client.

Now, Boris Johnson loves a PMQs courtroom analogy - repeatedly taking shots at Keir Starmer’s previous career as a high-flying lawyer.

But in their first cross-examination of the new term, Starmer looked like a professional who is across his brief.

And Johnson looked like a desperate, delusional defendant who insists on representing himself in the dock against all advice.

Sitting on the green benches, surrounded by nothing but briefing papers instead of helpful Tory colleagues, the PM cut a lonely figure.

Sadly, for Johnson, PM doesn’t stand for Perry Mason - and every “a-ha” attack line he blurted out to bamboozle the opposing barrister fell embarrassingly flat.

Starmer won’t say schools are safe, he insisted. Wrongly, as it happens. Starmer has repeatedly said kids should return to school this month.

Starmer 'supported an IRA-condoning politicia', Johnson claimed in a bid to smear the Labour leader for having served under Jeremy Corbyn.

Which is a bit of a stretch considering Starmer was literally in charge of prosecuting terrorists in Northern Ireland - and a bit mean considering today Starmer’s birthday.

Speaker Lindsay Hoyle played the exasperated crown court judge, cutting the amateur legal eagle off and directing him to answer the question. Johnson, it’s fair to say, did not appreciate the intervention.

Starmer, for his part, barely needed to try. All he needed to do was turn up and ask the PM to string a sentence together, a task of which Johnson appeared entirely incapable.

The waffle simply doesn't work in a pared down Commons chamber - especially when your browbeaten backbenchers can only muster an anaemic whimper of support.

Isolated, deflated and resigned to a life-sentence as Britain’s most incompetent Prime Minister, Boris Johnson might wonder if those rumours about him quitting in six months weren’t such a bad idea.

No further questions, your honour.