He laughs and says that sounds good, that sounds interesting. I stand still and look at the playground. An overweight Arab boy is panting over the sand pit. His Filipino nanny stands over him, her skinny arms on her hips. This job has taken her from her lush homeland, through Doha or Bahrain. For a few months she will walk London’s tired grass. In holiday photos and video clips, she will be an exotic flower in the background.

‘I am sorry to hear about your broken engagement,’ he is saying.

I mumble something in reply.

Hisham’s voice sounds distant as if he is looking away, ‘The need for money can make the throat go tight. But some people have neither morals nor restraint.’

The last thing I want is to discuss my ex. So I make my voice light, ‘You’ve become a philosopher, Hisham.’

‘Yes. And I’m intrigued by the Circle Line – by all things that are inaccurately named.’

‘Pardon?’

‘In the Underground. I took the Circle Line and it didn’t bring me back where I started. Apparently the trains no longer run a continuous circle. Instead they travel in a semicircle and there are now actually two routes.’

I remember now, this quirkiness of his. How he was sometimes geeky, sometimes soulful. How he earnestly revealed information, things he must have read about or remembered from TV. ‘Merlin is a kind of falcon. The Nile is the longest river. Seaweed is edible.’ Now he wants me to show him around London.

We agree to meet up tomorrow; perhaps it won’t be as hot as today. It is at this time of year that I miss Abu Dhabi the most. I miss the spacious malls and the blast of the air conditioners. Here, it is as if the sun of the Empire has come to pay respect. London swells with planeloads of tourists. Tourists with big appetites, cash heavy, mouths watering, eyes popping.

‘Bloody foreigners!’ screeches a harassed mother as they stampede her and her infant, getting on a bus in Oxford Street. ‘Every bloody summer.’

The buses are full of women. Women with pushchairs and little old women, shaking away. Dreamy schoolgirls stalked by bullies. The slow red buses are dignified like the Queen.

City of generous absorption, of waddling matrons in black abayas and face veils consulting Harley Street specialists, of sulky adolescents seeking distraction in Madame Tussauds. Ancient Egypt’s gold, lying cold in a museum. The tennis at Wimbledon, the pigeons in Trafalgar Square. And an order, a fairness; an obligation to make things better even in some little way. Under Marble Arch I feel the weight of history.

In the streets: nose rings, dreadlocks, skinheads, pin dug through an eyebrow, man dressed as woman, dog dressed as man, a placard raised high – Jesus Is Coming.