Terry was assigned to me as my illustrator when I wrote an educational book called Swinging on the Clothesline, back in 1991. The publisher said, “We know this guy’s got a good sense of humour. We think you’ll get along really well.” They were absolutely right. Terry drew these kids swinging on the clothesline at a very high speed, flying off into the ether. I was like, that’s what I’m about. He created everyday portals into wild fantasy.

The first time we met in-person was at a festival around 1995. I was quite awestruck – this was the great Terry Denton, winner of the CBCA Picture Book award! I watched him do a session with the kids where he was drawing cows in various emotional states: “This is a terrified cow. This is a peaceful cow. This is a cow in love …”

He was well-established; I was not. Publishers were still terrified of me then. “We find your stuff very entertaining,” they’d say, “but we can’t see any point to it.” But Terry did. He said, “Tell them I’ll illustrate anything you do, because I love the freedom I get from your words.” We both loved Monty Python; that was our shared reference point for everything. He was a true clown. He could make something funny out of nothing. I was very happy to work with him for so long, but also that I got to tap into his seemingly inexhaustible flow of nonsense.

Terry famously filled all the margins of the “Just” books with little doodles and flick pictures on the corners. This was my idea, because I’d been a high school English teacher and I’d watched how kids chose books in the library – they would flick through to see how big the print was. If it was really small or there weren’t any illustrations, they’d go, “Nup, not reading this.” I didn’t trust my audience to want to read a book. So I said to Terry, I don’t want regular illustrations of the story – I want you to do little flick pictures so they start laughing and showing each other, and maybe I’ve got a chance at getting them to read the first line. Terry took that ball and ran with it, to the point that he created an entire other book in the margins. Sometimes he’d get bored and he’d drop a piano on me. The kids would draw my attention to it – they’d go, “Do you know Terry dropped a piano on you?” I’d say, “No. Did he really?” And they’d go, “Yeah, look, it’s on page 169.” I would say, “Right, when I get home, I’m going to smash him with a piano.” The kids thought we lived together, which we just loved.

I loved it when he would turn up at my front door for what we would call “a Terry Day”. It happened every few months. He’d turn up in his flannel shirt and no shoes. We spent a lot of time together in those early years, really getting to know each other so that we could write and draw without stepping on each other’s toes. There was a lot of laughter, a lot of talking and, by noon, I’d go, “Come on, we’ve got to get something done!” And something would inevitably come out of all of that.

I think what he liked about me was I gave him permission to go to crazy places. He had a whimsical, gentle side. He was very relaxed. He wasn’t very fussed by a deadline or expectation. I was the opposite. I’d say, “Come on, Terry, we’ve got a deadline. We’ve got to get this thing done.” And he’d go, “Yeah, do you like this picture I’ve done of my finger?” It was fantastic that we were able to manage that so harmoniously over three decades.

When we did the “Bad” books, we were public enemy number one. We were accused of encouraging kids to run across the road with their eyes shut. I was on A Current Affair! Some bookshops refused to stock it. The punk rock troublemaker in me was delighted. Meanwhile, Terry was nowhere to be seen. He was very smart in that way. He didn’t waste energy arguing.

In the “Treehouse” books, Terry and I became characters. They’re neither child nor adult – they’re somewhere in between. Occasionally I overhear a child complaining to their parents: “Andy’s not a child, mum. He’s an old man! They lied to me!” But I think it’s a tribute to Terry that he could make it so convincing. Our characters fought horrendously. He hits me with a giant banana and knocks me out cold in that first book – there’s six pages of darkness because I’m unconscious. No matter what nonsense we dreamt up together, he could make it seem reasonable in his drawings. A never-ending staircase? Sure, no problem; Terry and Andy climb it for about 25 pages. When we got together, our inner child came out and started goading each other. And it was that playfulness that kids really picked up on.

I think Terry was happy to be in the background. He was a private guy, probably a little more introverted than people might assume. He was very funny and gregarious. But he really loved, in his own words, slapping ink on paper. That was his happy space. The Treehouse books gave him enormous exposure and took up a lot of his time because there’s probably a thousand drawings in every book. Sometimes he would draw something that wasn’t what we wanted but sometimes it was better, and I would change the plot to match. Fifty per cent of the authorship was Terry. And 50% of the royalties too – I always bent over backwards to give him the credit. I’d say, “Do you want to come on tour?” and most of the time he’d go, “Nope!” “So you’re OK for me to go out and take all the love and the congratulations?” “Yep!” He did come on tour at the height of the Treehouse mania, but he just wanted to draw and paint.

It was sad that his health declined so quickly after we finished the final Treehouse book. As it got worse he pulled down the shutters and concentrated on his health, with his family around him. We communicated by letter – and drawings.

There has been an enormous outpouring of love for him since he died. My biggest regret is that I’d love him to be around to experience all of this. He won the hearts of so many children. My favourite thing to do at a stage show was to say, “Right, who’s your favourite, me or Terry?” then I’d get mad at the audience for liking him better. But I always knew the answer.