The latest heatwave reminded me of my brief career as a marijuana farmer. This wasn’t in the summer of 1976, when I was 13, but three years later, by which time my family had moved to Devon. My father had been commissioned to write the biography of Leonard and Dorothy Elmhirst, the founders of Dartington Hall, a utopian community in South Devon, and wanted to be nearer the archives and the couples’ friends and colleagues whom he was planning to interview. Having been brought up in London, I was terrifically snobbish about how behind the times the local teenagers were – still wearing flares and listening to Status Quo, gawd help them! But at least the house we’d bought came with a tiny bit of land. That meant I could cultivate my own cannabis plantation.

No internet back in those days, so I ordered a growers’ guide from one of the small ads in the back of High Times, the weed smokers’ bible. The advice was to germinate the seeds at the beginning of February and keep the seedlings inside in a warm place with artificial light, then plant them outdoors in June with a view to harvesting them in September. My sister, who was two years older and a pupil at Dartington, an ultra-progressive independent school, supplied the seeds.

I lived in the garden in what we referred to as ‘the hut’, but it was actually more of a guest house with electricity and running water. It didn’t have a bathroom, but it had a sink behind two cupboard doors and it was there that I set up my indoor greenhouse. I bought a fluorescent tube, attached it to the J-shaped pipe below the sink, rigged up a switch on a timer and placed the seed tray beneath it. Bingo! My very own ‘grow op’, as we drug lords like to say.

Everything was going swimmingly until my father strolled into the hut one day, saw the light coming from the sink area and opened the cupboard doors to investigate. Oh no, I thought. The federales have arrived.

‘How many times have I told you?’ he said. ‘You mustn’t leave lights on. It’s a terrible waste of electricity.’ With that, he turned off the fluorescent tube and stalked out of the room.

At the time I thought he must have seen the plants, realised what they were and decided to turn a blind eye. Perhaps he was glad I finally had a proper hobby and wasn’t spending all my time reading the Fabulous Furry Freak Brothers and watching Wacky Races. But I now realise he was just so fanatical about conserving electricity that it gave him a kind of tunnel vision. Needless to say, fast-forward 40 years and I am exactly the same. I regularly stride into my children’s rooms on school days and unplug all the appliances that are quietly humming away. If one of them was using artificial light to cultivate cannabis plants I doubt I’d notice either, as I furiously extinguished the bulb.

Summer arrived and I duly transplanted my crop. I had a dozen healthy plants and I cleared an area of ground in the middle of a stinging-nettle patch to create a little south-facing glade. I reasoned that the nettles would provide a natural security fence and stop my efforts being seen by any nosy neighbours. It worked, too. I watered the plants every day, and during the months of July and August they grew tall and bushy. I even began to fantasise about producing more than enough leaves for my personal use and selling the excess to my sister’s drug-addled friends at Dartington.

We were due to go on a family holiday to the south of France in the last two weeks of August and I started to worry about whether the plants would survive if it didn’t rain. I decided to offer my best friend, Nick Robotham, who lived nearby, a deal. If he promised to water them every day while I was away, I would let him have one of the plants. But he couldn’t under any circumstances tell anyone where they were. It would be our secret. He accepted the deal, swore an oath of loyalty, and I led him along the secret path through the nettles to my little garden.

Two weeks later, when we arrived back at the house from France, the first thing I did was to inspect my marijuana patch. I was excited to see how much the plants had grown by, and whether they’d started to flower. You can imagine my heartbreak, therefore, when I discovered my secret had been betrayed. All that was left of my 12 beautiful plants were a few sad-looking stumps. I later discovered that Nick and a few of his mates had helped themselves to the plants, chopping them down weeks before they were ready, and organised a party in the local woods.

My career as a marijuana dealer had been nipped in the bud. I never forgave the little bastard.