How we met: Genevieve Webster & Michael de Souza

'If we were a band, he'd be the frontman and I'd be the drummer. He's such a big character while I'm naturally much shyer'

De Souza says: 'What I love about Genevieve's illustrations is their childlike quality, the simplicity of how they convey emotions; it tugs at the heartstrings' (Jean Goldsmith)

Michael de Souza, 59

Born in Trinidad, De Souza moved to London in his youth, and became a swimming instructor. His first children's book, 'Rastamouse and the Crucial Plan', illustrated by Genevieve Webster, has spawned three sequels and a stop-motion animated TV series on CBeebies. He lives in west London

I was a kids' swimming instructor at the Kensington Sports Centre, and I offered tips when I saw adults with almost-perfect strokes. Genevieve's breaststroke was a bit skewwhiff and needed a bit of advice, and she appreciated what I had to say. We were living around the same sort of area and after that we bumped into one another from time to time.

I knew she was in publishing [working as an art director], and I had a draft for a swimming book called Professor Splash – part instruction manual on enjoying swimming – and I approached her for her thoughts. A friendship developed as we share a love of language; she also liked Caribbean culture, and I introduced her to a lot of reggae.

After I'd had a daughter I spent more time at home, to look after her, and started to write poems and rhymes about a mouse that lived in a council house; I grew up with mice running round our streets in Notting Hill. And one day when I went to visit Genevieve, I left her some notes that I'd written. A few days later, she said, "I've got something to show you."

She'd drawn this little mouse with a little Rasta hat. I was bowled over, as I didn't have any idea what the mouse would look like – I'm not a visual person. Everyone saw me in that illustration, but I couldn't – and still can't. We started writing together and it was very natural, as our senses of humour gelled.

We opted to self-publish, as the publisher who offered us a deal said, "Rhyme doesn't work always overseas." They tried to play it safe, but it's a joke – how does playing safe with your imagination work? What I love about Genevieve's illustrations is their childlike quality, the simplicity of how they convey emotions; it tugs at the heartstrings.

Genevieve's a perfectionist and she's given me a different approach to life: it's the way she thinks about things before she puts them down on paper, and the standard of her work.

As a team, we work well because we've had a lot different experiences – I was born in Trinidad, she is from Canterbury – but we share the same goal: get Rastamouse into the psyche of the British public and help people realise the contribution Caribbean people have made towards the British language.

We were happy when we handed our creation over to CBeebies, but we were surprised by the initial criticism of the TV show; I think some sections of the Caribbean community [who labelled it racist] didn't realise there was a genuine black Rasta involved; they thought it had been concocted by the BBC and handed over to a white writer.

Genevieve Webster, 48

After studying graphics and illustration at Canterbury School of Art, Webster worked as an art director at Heinemann, illustrating children's books, before teaming up with De Souza in 2001. She lives in north London

I was swimming every day at the Kensington Sports Centre's pool, where Michael taught swimming lessons. What stuck me was the way he interacted with children in a natural, uninhibited way. He'd use funny rhymes to explain the movements and techniques of each stroke and it seemed to work well, bringing lightness and a fun atmosphere for kids scared of being in the water.

I was working as an art director at the publisher Heinemann, and illustrating children's books was my great passion, so his connection to the kids attracted me and we got talking. He told me he'd been working on a book that taught kids to swim, so I suggested he come into Heinemann to discuss his idea. When I saw it, it wasn't something I would have published: I didn't like the illustrations and I felt the strength of his method was so much more about how he interacted with those kids in person.

But we struck up a friendship as I also had a love of the Caribbean dialect – I love the rhythm and warmth of it – and he's got an extensive knowledge of reggae, of which I'm a huge fan. We hung out a lot together, and went swimming a lot, too.

One day, in 2001, I happened on a poem he'd written about a mouse in a council house, and I ended up doing a drawing of one, part inspired by the poem and part inspired by him, and I said, "Look at this." We decided it was something special and that we'd write a story for this mouse together. A lot of kids go to school and do one bad thing and are labelled a trouble-maker. And I suppose that's what Rastamouse became about: seeing the positive, saying, OK, you made a mistake but this is where you can turn it around.

Our dynamic worked as we could be honest and open. I was happy to say to Michael, "No, that's rubbish," if the rhyme was feeling forced. We were offered a contract but a defining moment came in our decision to self-publish the first book, as we didn't want the idea to be diluted.

If we were a band, he'd be the frontman and I'd be the drummer. He's such a big character and he's so good at interacting with people. I'm naturally much shyer, which is why touring schools has been a lovely experience for me, as with Michael I feel able to go up on stage and read with him, which I've loved.

As we get on so well, we get asked all the time if we are an item! I'd probably make that assumption myself, but no – even if people don't believe us, we are just good friends.

The fourth Rastamouse book, 'Rastamouse and Da Micespace Mystery' (£6.99, Macmillan Children's), is out this autumn (rastamouse.com)