When Martin Waddell started work on Tango’s Baby, his latest novel for teenagers, he tried to write it as his literary alter ego, Catherine Sefton. The book began as the story of a young girl who has a baby and hides it in a hen house in rural Ireland, but Catherine Sefton couldn’t pull it off. Martin Waddell took charge, adopted a male point of view, and the book gradually metamorphosed into the study of a boy on a rough council estate who strives, unsuccessfully in the end, to be a good father to his child.

Tango’s Baby is, for its author, an important new departure. Narrated by another boy on the estate, who tries to piece together what really happened between Tango and his girlfriend, Crystal, and why it all went wrong, it draws on a large cast of characters from Tango’s community, finding only partial truths. It is broader in scope than Catherine Sefton could have made it; where she would have been confiding and intimate, Tango’s Baby is more ambitious, more challenging and also, perhaps, bleaker.

For Martin Waddell’s readers, the book is another demonstration of this author’s immense versatility, his refusal to be neatly categorised and his determination to keep trying new things. Up to now, he has mainly been “Martin Waddell” for what he calls his “silly books” - such as the Napper footballing series (Puffin) - and for his 40-odd picture books, which include his best-selling Can’t You Sleep, Little Bear? (Walker Books), and other favourites like Owl Babies and Farmer Duck (both Walker).

Catherine Sefton meanwhile has pursued a rather different career as a writer for older children of ghost stories, thrillers and adventures, such as Along a Lonely Road (Puffin) and Starry Night (which won the 1986 Other Award) many of them set against the troubles in Northern Ireland. She first came into being in 1972 with the publication of In a Blue Velvet Dress (Faber) a gentle pastiche of a Victorian children’s book - “the first book I was really happy with” - which was so vastly different from the six comedy thrillers that had launched Waddell’s writing career that his publishers suggested a pseudonym.

“It just came into my head,” Waddell recalls. “Catherine was a name I liked. Sefton was my grandmother’s name.” But he rather wishes now he had not gone for a female identity. “It would have been a unisex name, if I’d been around on the day it was decided,” interjects his wife, Rosaleen - partly because of the questions about it that have dogged him ever since, and because he feels that it lost him a male audience. “A lot of teenage boys simply will not read a book with a woman’s name on the cover”.

Martin Waddell lives in the small, seaside town of Newcastle, in County Down, a stone’s throw from the cottage to which he was brought as a baby in 1941, to escape the bombs falling on Belfast. His study, which looks over the beautiful Mourne mountains and the woods that he roamed for much of his boyhood, is almost entirely lined with his own books. Just in the last 10 years, he has published 160 of them. In a good week, he says, he might have completed texts for four picture books. More than 16 new titles are in the pipeline for publication in the next couple of years, and in the dozen or so green files that lie beside his desk are the germs for many more. Thin, pipe-smoking and softly-spoken, Martin Waddell, as he talks about his work, radiates the purposefulness, the energy and the commitment to writing that have made him so successful an author.

He is, though, sensitive to the charge, that has sometimes been made, that he is simply churning books out, sausage-machine-style. “There are lots of books because the ideas are there. I work very hard, and I enjoy writing, it’s what I do. I’m doing fewer books now and the ideas don’t come so fast - but I don’t see any reason to stop.”

His life has not always been so comfortable and so prosperous. His first love was football, and on leaving school at 15 with his parents’ marriage breaking up and not a qualification to his name, he went to London and persuaded Fulham FC to sign him on. He played for Fulham’s junior team for a year before deciding that he was never going to make it professionally, and then fell back on his second love, writing.

For 10 years he lived in shabby London bedsits, more and more homesick for Newcastle, and writing and rewriting the same adolescent novel about home and unrequited love - until his agent suggested he tried something along the lines of Len Deighton’s The Ipcress File. The thrillers followed, and enough money to take him back to Northern Ireland, where he met and married Rosaleen in 1969, settling in Donaghadee, a loyalist town just outside Belfast.

Two sons were born, Tom and David, and Waddell was just getting into his stride with his children’s books, when he was, as he puts it, “blown up”. A bomb in the Catholic church blew up within six feet of him, miraculously not killing him but leaving him badly cut and buried beneath the rubble. It was another six years before Waddell could recover his writing career. A third son, Peter, was born, Rosaleen went back to teaching, and Martin stayed at home looking after the children, prone to depression and weeping, but trying desperately to write whenever he got the chance.

“I love the children very dearly, but at the time, looking after them was totally gruelling. What I didn’t know was that I was sitting on the richest vein of ideas, building up what became Can’t You Sleep, Little Bear, Farmer Duck, and so on.”

In 1985, a five-book contract from Walker Books got him financially off the ground at last. Can’t You Sleep, Little Bear?, a touching and profoundly human story of a bear who is afraid of the dark, marvellously illustrated by Barbara Firth, hit the jackpot three years later, winning the 1988 Smarties Book Prize, and has sales to date of nearly two million.

“You need a big emotion at the centre of a picture book, that the child can identify with,” says Waddell. “A good book gives the parent a scenario, that he or she can adapt and talk about. Using rhyme, rhythm and repetition, with the words closely interlinked with the pictures, it leads to a kind of reading, where the child knows what words come next and can anticipate them.”

Although Waddell is adamant that “silly books” are also very important - “because children have days when they just want to giggle” - perhaps his main thrust as a writer, in his books for children of all ages, is wanting to help them, through his story-telling, confront the fears, or worries, or dangers they may be experiencing. While for a small child it may be fear of the dark, or, as in Owl Babies, wanting your mummy to come back, for a teenager, the pressure to conform, to take sides, to see strangers as “the enemy”, are subjects that he returns to again and again, often in the context of Northern Ireland. Of Scottish Presbyterian stock, but married to a Catholic, he has himself resolutely refused to take sides during the conflict.

“Seeing my own children growing up here, witnessing sectarian violence, I felt I had to say things. In my books, I try not to tell children what to think but to make them think - to make them think about what’s going on from the other end.

“I feel I’m doing something valuable in giving them teenage characters to read about. I’m trying to clear up some of the terrible confusions of being a teenager. Adults are often not terribly interested.”

TANGO’S BABY. By Martin Waddell. Walker Books Pounds 8.99. 0 7445 2497 0