‘Yours?’ I said to the woman watching the mechanic poring over the latest-shape Renault Mégane for faults. (I was waiting to have a word with the mechanic about my Clio.) ‘Yes. I don’t like it,’ she said. ‘All my life I’ve driven German cars, and then I got this one, and I just can’t get used to it.’ ‘Why did you change then?’ I said, annoyed by the snobbery. ‘I’m a spirit medium,’ she said. ‘I have lots of wealthy clients. I was working with one in her home, and it came into my head to say to her, “He says you must give everything away, including Bella.” I didn’t have a clue who or what Bella was. The client was dumbfounded. It turns out that Bella was what she called her Mégane. She gave it to me on the spot, just like that.’

I looked at her for the first time properly. Small, mid-sixties, sun-wrinkled face, hippie-chic clothing, sandals. Stupidly proud, too, of defining herself as a spirit medium, I thought. Presumably it made up for deficiencies in other areas. It’s amazing the sorts of people one meets at Johnny Derby’s workshop. It’s like a sitcom. ‘Well, if it was a supernatural gift, you’ll just have to put up with a French car, then, won’t you?’ I said.

It was a bit too early in the day for me to be impressed by elderly hippie spirit mediums whose wealthy clients gave them brand new Renault Méganes on the supposed instructions of dead relatives. So I took myself off and sat in Johnny’s new waiting room. Moving belatedly with the times, he has installed a glass-sided capsule for middle-class customers to wait in while their cars are MOTed. It has a comfortable sofa, a coffee machine (free) and a wastepaper bin. The only reading material is a neat foot-long row of Observer’s books: Aircraft; Automobiles; Postage Stamps; Firearms; Horses and Ponies; Birds; Old English Churches; Coins; Grasses, Sedges and Rushes — you name it. I fingered out Horses and Ponies and sank back with it into the sofa.

I’m reading the last volume of theatre critic James Agate’s diary and commonplace book, Ego 9. This large and lovable ego, son of a wholesale linen draper, conspicuously crowned his deep love and knowledge of theatre, Shakespeare and French literature with a fierce and scathing anti-intellectualism, which becomes all the more credible when one learns that his other great passion was Hackney horses, on which he was a world authority and Britain’s top show judge. I liked him all the more when I read this. Unfortunately, I hadn’t the faintest idea what a Hackney horse is or was. Johnny Derby’s new, gentrified waiting room was the place to find out.

A Hackney horse, I read, is basically your Norfolk Trotter, a riding horse developed in the 14th century and infused with Arabian blood in the 18th. (The Norfolk Trotter also evolved into the Norfolk Roadster, a heavily built horse used for both riding and working.) In the 1820s a Norfolk Trotter called Bellfounder covered 17 miles in one hour with 14 stone in the saddle: faster, in other words, than an Audi R8 on the M25 during rush hour. Hackney horses today have a high-stepping gait.

Armed now with a more complete image of James Agate in the show ring, I ventured back into the ramp bay to see if Johnny was now at liberty to have a word. He was still testing the emissions. The spirit medium adroitly intercepted me to try out some more of her boasts on me. ‘When will your car be ready?’ I said. She had no idea. We stood and watched Johnny run the emissions-testing machine. ‘I do police work, sometimes,’ she said. ‘They contact me when they are desperate.’ ‘And do you charge them?’ I said. ‘Oh no,’ she said. ‘I have so many wealthy clients, I don’t need to. They might give me a bottle of champagne if I am able to help them.’ ‘For example?’ I said. She wouldn’t go into details.

‘And did you have the gift as a child?’ She did, she said, and assumed everyone had it. ‘And you are simply a conduit?’ Yes. It was exactly like turning a radio on and off. ‘And you make a good living out of it?’ Very much so. ‘And what are the spirits saying about me?’ She laid a sacerdotal hand lightly on my shoulder. ‘Stop saying “try” to yourself. Every time you say “try” to yourself, your body is physically weakened,’ she said. ‘I’ll come back later, Johnny,’ I shouted, and walked away towards the road. When I was 30 yards away she called to me. I turned and saw her smiling and wagging an admonitory forefinger at me. ‘Remember! No more “try”!’ she said.