It’s hard to describe how heroin feels. William S. Boroughs called it “vegetable serenity”. Melvin Burgess called it “Chinese magic”. To me, heroin felt like waking up with the sun shining on your face, in clean, silken sheets. It felt like pure contentment – at least for a while, until I came to know the torment that an addiction would bring.

The first time I noticed people taking heroin, I was 20, at a house party, and in my second year of university. People were slipping off in small groups into closed rooms whilst everyone else whispered about what they were doing. The party belonged to a musician who my friend Ed had met at AA, and a couple of weeks later, he took us to another party where people were doing it, at a woman’s house.

She was older than us — an artist with outrageous stories. She was casually smoking heroin off a mini Martell bottle and passing it around. At first I said I didn’t want any. But then I got curious. I had moved to London to experience things, and I wanted to know how this felt. After inhaling a few times, I was completely underwhelmed. ‘Was this it?’ I thought. I felt warm and comfortable, but there was no extreme, debilitating high like I’d seen in films. No after-effects.

A few weeks later, I did the woman with the Martell bottle a favour and as a ‘thank you’ she offered me a tiny bag of heroin. I said I didn’t want it — I wouldn’t do anything with it anyway — but she told me to take it as a gift. It sat in my room for a month or so, until one night I finally opened the bag with a close friend. We orchestrated what we thought was a poetic experience, with a record playing and candles lit. We smoked it and I vomited at first, but persevered, smoking small amounts throughout the evening, talking and talking until the early hours. The next day I didn’t think about it much. It was an out of the ordinary experience, sure, but I had university and work to get back to.

The rest of the bag of heroin sat in my room. But the following weekend not much was on, so I invited my friend back to hang out and smoke again. Like having some cocaine on a night out or smoking weed at a friend’s house, this would be something I only did now and then, with certain friends, I thought.

When the bag ran out I replaced it. It was cheaper than cocaine and alcohol – £10 could have me high for two days. Soon I was getting it regularly, through “friends”, but I noticed that each time I took the bag off one of them, they had stolen from me a little more, giving me less than they should. So I started to seek it out on my own from dealers who I’d previously bought weed or coke from. As I began to buy it by myself, it also became less social – something I would do on my own. My friends were staying in a lot, studying for our third year exams at university, and I pretended I was doing the same. Only, by then I was smoking heroin three or four times a week. And the worst part was that I was functional; I could study and go to lectures with no hangover, no comedown and no repercussions. I was getting good marks. I thought of heroin as my treat — if anything, I told myself, I was being “good” because I wasn’t going out all night.