I remember the moment when I came up with the name for the older trumpet player, Joey “The Lips” Fagan; it felt like a good night’s work. I remember smiling – grinning – as I looked down at the name on the copybook page. It was so silly, but real. “Fagan” came out of the Dublin area phonebook, and “The Lips” came out of my head.

I started The Commitments in January, 1986, during the Christmas holidays, a few days before I went back to work as a secondary school teacher. I finished it in July. I typed out the final sentence – “Deadly, said Derek” – on a portable typewriter I borrowed from my mother. I like to think that I typed that sentence at half-time during one of the World Cup matches being played in Mexico; I’ve made the claim before. It might be true; it probably is. But 34 years later, I no longer remember, or I never did.

But I do remember Joey The Lips. I was living in a bedsit very close to where I live now. Whenever I needed a name for a new character I went down to the hall and took the phonebook from beside the payphone and bought it back upstairs. Jimmy Rabbitte, the Commitments’ manager, came out of the phonebook, and most of the band members. (Imelda’s surname, Quirke, was the name of a chipper on Amiens Street.)

I discovered that night that there’s nothing quite as exhilarating in the writer’s life as bringing a character to life with a good name. He was going to be Joey The Lips, never just Joey. He’d be the older man, the link to the musical past, the 60s, the route to black America. I was thinking of Rico Rodriguez, the trombone player in the Specials, and Saxa, aka Lionel Augustus Martin, the middle-aged sax player in the Beat. The nickname – The Lips – would be the reward for his prowess on the trumpet, but it already hinted at other rewards. The closed door – the plot – started to open in front of me. With a name like that, I’d have enough to keep me writing for months.

I don’t smile or laugh as I work, when I write a line that might make a reader laugh. But I think I must have laughed back then, when I was starting, coming up with my own rules. When I began to see what I could get away with, what I could do with grammar, spelling, song lyrics, sounds and names lifted out of the phonebook. I see now when I look at a page of The Commitments: I put all those words and names and sounds into a blender. I was alone, luckily; nobody told me not to.

The names, I think now, are the most important thing in the novel. The names I gave the characters, and the names they gave themselves, and the freedom those names gave them. The character I named first, Jimmy Rabbitte, was able to give new names, extra names, to the other characters – Derek “The Meatman” Scully, Deco “Blanketman” Cuffe – personalities he was inventing, I was inventing, because I’d invented Jimmy. I shared their excitement – I think I did – as Jimmy announced their new “soul” names. And I was aware, all the time as I wrote: “I’m doing this – there’s no one here, except me. This is fuckin’ great.”

But the novel – I knew I was definitely writing a novel that night, when I decided the band needed an older member and I went downstairs to get the phonebook. I always put it back, beside the payphone, when I was finished with it. Now, I wish I’d kept it.

• Love by Roddy Doyle is published by Cape (£18.99). To order a copy go to guardianbookshop.com. Delivery charges may apply.