At eight o’clock in the morning a nurse injected me with a radioactive marker and told me to go away and amuse myself for three hours. The metal chairs in the waiting room were uncomfortable and there was nothing to rest my head against. So I wandered outside the 19-storey hospital to look for somewhere to lie down. Every outside space was taken up with parked cars, thousands of them everywhere you looked, some of them jammed in opportunistically at fantastic angles.

Eventually I found a patch of rough grass between two car parks. The grass was strewn with stones, rubble and litter but I lay down gratefully, resting my head on my folded hoodie. A prim pair of collared doves patrolled for food scraps discarded by those hospital workers who preferred to sit in their cars to smoke and eat their lunchtime roll. The sun bounced between scudding clouds. A kind soul returning to his car stopped to ask me if I was okay.

I was on the brink of sleep when I was bitten on the stomach by a very small, very aggressive ant. Sitting up, I found several others running feverishly around on me, presumably looking for a way in, though not in sufficient numbers to send me off to look for an alternative spot. I assumed they were a small scouting party. Another one bit my neck. I slapped him to death but carefully flicked off the others. Lately I have lost some of my former arrogance concerning the grandeur of my life compared with that of small biting insects. Also I was investigated by a military-grade horsefly with massive feet, beautifully liveried like a starling, but I gave it the brush-off and it shot off to try its luck elsewhere. I lay there dozing among the paper cartons and sandwich wrappers for two-and-a-half hours, occasionally flicking off the more persistent of the ants. It wasn’t comfortable but it was much better than the metal chairs in the waiting room and the gusting breeze felt pleasant on my face.

Half an hour before my appointment, I brushed myself down and returned to the waiting room. Shortly after that a nurse led me into the room where the scanner was and ordered me to empty my pockets, take off my glasses and lie down on a narrow slide. Sometimes you have to lie with your arms above your head, which can be painful, but on this occasion I was allowed to keep them down by my sides. ‘Ne bougez pas!’ barked the nurse, waggling a finger at me. ‘Don’t move!’ ‘For how long?’ I said. Again in English she said: ‘Forty-five minoots. Not move!’

It was very wonderful to me that the soldiers guarding Queen Elizabeth’s coffin in Westminster Hall could remain perfectly still for 25 minutes before being changed. Suppose they had an itch? It must have been torture. Yet here I was a week later being asked to lie perfectly still in a tube with my nose almost touching the tube ceiling for a full three quarters of an hour. From kick-off, in other words, until half-time of a football match.

Past experience told me that if I moved a muscle the machine operators would come flying out of their glass box and go absolutely spare at me in Marseille-accented French and we’d have to start all over again. So I steeled myself to see it through, helped by a fortunately remembered sedative.

The machine had been humming around me for about ten minutes when I felt the first itch on my right cheek. It drove me nearly insane. I thought of tropical beaches and lapping waves. I thought about every dog I have ever known well. I took a mental stroll on Southend pier and had a plate of winkles at one of the shellfish stalls at Old Leigh, doused with lashings of malt vinegar and white pepper. Those winkles and some extreme facial gymnastics did the trick.

For the next five or ten minutes I felt only a pleasant drowsiness. The machine hummed intelligently. Then I noticed a new tickle on the back of my leg. I braced and rubbed it surreptitiously against the supporting surface. Beneath my jeans the tickle moved steadily upwards towards my thigh. Dogging its gigantic foe from the hospital car park to the inside of a million-euro scanner – in ant terms a distance of about a thousand miles – the ant was taking its scouting duties very seriously indeed and besides cursing it I gave it its due respect. The ticklish activity of a very small, very aggressive ant in my jeans vs the ire of a working-class Marseille nurse if I flinched was one of the most difficult decisions of my life. Perspiration broke out on my forehead.