If Boris Johnson had a little more self-awareness he might have reshuffled himself last week. The trip to the United Nations general assembly in New York was supposed to be the fun part of the job. A chance for the prime minister to do the things he likes best – rubbing shoulders and making crap gags with other world leaders – while his juniors were left back home trying to maintain the energy supply and offer vague reassurance that Christmas would not be cancelled. Yet instead he found himself repeatedly on the back foot, sounding as downbeat as all those ministers he had sacked for not showing enough mindless, Tiggerish enthusiasm.

To make matters worse, most of the damage was self-inflicted. Trying to drum up global support for the Cop26 summit by reminding everyone he had written several articles 20 years ago that had been sceptical of climate change wasn’t the brightest idea he had ever had. It just made him look like the untrustworthy chancer most people thought him to be. Nor did his excuse that when the facts changed he changed, help greatly. No one could remember the facts about climate science having changed that much over the last two decades.

After that, things went steadily downhill. First he admitted there was only a 60% chance of getting countries to stump up the GBP100bn to fight climate change, Then he effectively conceded the UK was at the back of the queue for a trade deal with the US, having previously insisted the it would have a deal in next to no time and that those who claimed otherwise were in the grip of “project fear”. This was the kind of careless talk that cost other people their jobs.

Tuesday didn’t start a great deal better with a short interview with Savannah Guthrie on NBC’s Today programme. Boris had wanted to focus on climate change – apparently Joe Biden was so onboard with cutting carbon dioxide emissions that UK meat production was now under threat – but Guthrie mainly wanted to talk about Afghanistan.

How had the prime minister felt about the chaotic scenes in Kabul during and after the withdrawal of US troops? Johnson’s attempts at diplomacy just made him look out of the loop as he tried to maintain the evacuation of Afghanistan had been a logistical success. Guthrie looked amazed. No one had told her she was dealing with a halfwit. God knows what a failure would have looked like.

The interview ended with Boris fessing up for the first time that he had six children. Or, to be strictly accurate, six children he was prepared to acknowledge – with another on the way. He didn’t say whether there might be more he had forgotten about. Or if he could remember all their names.

Still, on the plus side for Johnson, he was 3,000 miles away from the UK, where Jennifer Arcuri was giving evidence via video link from Florida to the Greater London assembly’s oversight committee about how having had an alleged affair with Boris while he was London mayor in no way helped her to get on trade missions or to hoover up GBP126,000 in grants from the public purse. In the space of 90 minutes, Arcuri made a telling case that their’s was a transactional match made in heaven. Both she and Boris appear to share the belief that they were doing the other one a favour.

Arcuri’s recollection of events was crystal clear. She had been doing an MBA in 2012 and in the space of a couple of years had become the centre of London’s tech industry. She was the Bill Gates of Shoreditch who didn’t take no for an answer and would demand that people find another way to say yes to her. Without her, Bloomberg would never have moved to London. Even though the company had done so years before she came on the scene.

And as for the trade trips she may or may not have been on – Arcuri made it sound like nothing more than a coincidence that she would happen to turn up in the same cities at the same time as Boris and his delegations – there was no conflict of interest. If anything she had been the one who had been doing Johnson the favour just by being there. It had been she who had advised Boris not to bullshit the bullshitters and never to use public wifi. The kind of advice that money just can’t buy. Besides, she couldn’t help it if he had a crush on her. After all, it wasn’t as if it was a secret. Everyone knew. This at least had the ring of truth.

For someone so keen to parade her brilliance as an entrepreneur, both she and the committee were surprisingly reluctant to talk about her financial results. A quick glance in the register at Company House reveals that Hacker House, the UK company for which she is still a director, has assets of GBP93,000 and liabilities of GBP1.3m. Still, it sounds as if it was fun while it lasted. I guess you had to be there.