The best question time in town yesterday was not at the House of Commons but at City Hall. There, the most powerful Tory in the land, Boris Johnson, was facing his first grilling or, as he put it to London Assembly members: “I now submit to your catechism.”

Catechism? This caused a few titters, not least as most of us thought it was something to do with religion. But now, driven to the dictionary, I find a second meaning: “Rigorous and persistent questioning.” Hmmm. Could “The Mayor's Catechism” ever catch on? Like PMQs but with (much) longer words? Ken Livingstone, newt-lover and mayoral loser, had come to watch. How awful is that? He was even dressed for work in his usual beige suit and tie. Perhaps, like so many newly retired types, he still keeps to the old routine.

Red Ken now looked like Sad Ken, his face as lachrymose as a puddle of tears.

Those of us who saw Boris in his clown days knew that this was a toned-down version, but it was still a riot: a cross between Have I Got News for You and Mastermind (Boris's specialist subject was traffic phasing). It could become cult viewing, not to mention required viewing for students of Latin.

First, though, before your lesson on the Aeneid, this is Boris on the mysteries of traffic light rephasing. He denounced as ridiculous the lights at Trafalgar Square. “They are red for one minute 45 seconds and go green for only 12 seconds!” He vowed to fix this as the audience shouted “Yeah! Yeah!”

Boris also pledged to rectify the “appalling legacy of neglect” where 707 lights did not conform. “Pedestrians are having to sprint at 1.2m per second to get across the road.”

As he burbled on, a Green assembly member shouted: “Repetition!”

Boris ignored this and waxed on about how to make cars flow. “We could use Scoot ... ” He flipped his notes over, wacking the microphone with a thud. “That's for Split, Cycle and Offset Optimisation Technique.”

This went on for much, much, much longer than the Trafalgar Square red lights.

Then a Labour member called Val produced a new cycle helmet. “Do you believe in zero tolerance to minor offences, like riding your bike through a red lights?” she asked sternly.

Boris looked embarrassed. A minor fracas broke out with other assembly members objecting to the use of the helmet as a prop. This gave Boris time to regroup and to declare himself a changed cyclist who was now “punctilious” about observing lights.

Val jumped up to give him the cycle helmet. (Yes, it was this bizarre.)

Boris accepted, although he had just bought one, not for safety but because he wants to be “as anonymous as possible”.

A Green member called Darren declared himself opposed to the idea of a new six-lane bridge across the Thames.

So what, asked Boris, was Darren's idea for a new crossing? “Do you envisage a kind of catapult?” he asked, making a catapulting gesture at Darren. I could almost see Darren hover above the Thames before landing with a major splash.

“Cable car!” said Darren. Boris smiled at that.

And now for the Latin bit. Boris was being hammered by some Labour members about not following the correct process for appointments to his financial audit board.

“Non tali auxilio nec defensoribus!” cried Mr Mayor (an incomplete quote from the Aeneid, which means something like, as Hecuba would confirm, “this is ridiculous”.)

“Speak English!” the member shouted back.

Mr Mayor didn't like that. After all, no one ever said that to Virgil.

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