The Royal College of Art’s links with children’s book illustration go back a long way: Walter Crane was for a short period its principal, and Kate Greenaway was a student at what was then the South Kensington School of Art. Edward Ardizzone was a tutor at the college in the postwar years and on his retirement there appeared Brian Robb, a less famous, but in some ways equally distinguished, artist. Brian Robb’s work had a humane, wry, almost teasing character that makes me wish he had set his hand to more children’s books than he did. Brian Robb established illustration as a separate strand in the educational life of the college. I worked for him for 13 years while he was head of the Illustration Department, and took over from him when he retired.

However, the main part of the exhibition Still There Will Be Stories which opens at the college next week, is concerned not with the work of teachers, but of ex-students - more than 40 of them. The college has never had a children’s book illustration course or taught it as a separate subject; RCA students are postgraduates and their individual studies are pursued in one-to-one tutorials. And not all those who have taken to children’s book illustration have done so immediately or exclusively. Michael Foreman had published The General as a student, but it was some years - years in which he made his mark as an editorial illustrator - before he returned to the path that brought him to his present prolific eminence. Similarly, Emma Chichester Clark established her position as a book-jacket and gallery artist before the success of Laura Cecil’s Listen to This. She brought to her children’s books the same richness of tone and colour, and combined it with a sort of knowingly innocent air that allows her to encompass happily both the humorous and the poetic. Other artists - Nicola Bayley and Colin McNaughton are outstanding examples - had their potentiality as children’s book illustrators recognised when they were still students, and went straight into print.

The teaching of illustration at postgraduate level, as with other art and design disciplines, is not so much to do with teaching young people the practice of their craft - most students arrive knowing a great deal about that already - as with helping them to find their own directions, the true character of their own work. Nicola Bayley found hers while protected by a little curtain she had rigged up round her desk, and emerged in due course with a tiny portfolio (small enough to go into a handbag) full of characteristic hypnotic detail. Colin McNaughton seemed to know from the beginning where he stood (“somewhere between The Beano and Rembrandt” was his formulation) and the subsequent years of productivity have seen a growing confidence without any loss of the rapport with his readers that has always been one of his distinguishing features.

However, first steps are not always easy or straightforward. The first book illustrated by Angela Barrett (am I right in remembering a pink dragon?) showed her, I suspect, trying to fit herself into a publisher’s preconceived ideas, or her own about what a publisher wanted. Fortunately it did not take her long to find the way back to her real line of development, which led on to a sensitive naturalism which doesn’t preclude - in fact, makes possible - an aura of the mysterious, the haunted.

All these last three artists use detail in distinctive ways; this is not the approach of two more recent illustrators. Claire Fletcher and Lisa Flather are both recent winners of the Mother Goose Award, which welcomes each year a successful newcomer to the scene; and both are accomplished draughtswomen. Claire Fletcher’s work is realistic but animated, breezy, painterly. Lisa Flather followed the Natural History illustration course at the RCA and (like Mick Manning, who is also in the exhibition) knows how to draw animals and birds in an informed but informal way; her children’s books, by contrast, exploit the techniques of printmaking.

It’s possible to detect veins of stylistic affinity which run here and there through the work on show, but it is really diversity which is the essential feature. It has never been the business of the college to promote a house-style; rather to send its students off in all directions. But, if the intention of the show is to demonstrate the diversity of talents and approaches of the exhibiting artists, its purpose doesn’t end there; it means also to give some insight into the way illustrators work. Its presentation not only incorporates originals, but, concentrating on one or two books from each artist, shows sketchbooks, roughs and working drawings; layouts of pages and, perhaps most interestingly, printed sections of books, and sometimes whole books, displayed as a flat sequence of pages: a technique which should vividly illuminate the ways in which text and pictures interact as they flow through the book. Nor is the exhibition restricted to books; recent work in animation will also be on show.

And perhaps this look behind the scenes will elucidate the mixtures of depiction and narrative, of anarchy and order, of the real and the fantastic, which go to make up a children’s book; and help to plot the eddies and cross-currents which give this area of the illustrator’s craft its special fascination.

Still There Will Be Stories, The Art of Children’s Illustrators from the RCA. The Henry Moore Gallery, The Royal College of Art, Kensington Gore, London SW7 from November 17 to December 6. Speakers on the opening afternoon include Judy Taylor on working with Edward Ardizzone, Michael Foreman on fact and fantasy, Brian Alderson on children’s book illustration today and Russell Hoban and Quentin Blake on the relationship between words and pictures. Further details from Liz Ruth, RCA, Kensington Gore, London SW7 2EU. Tel 071 584 5020.

Quentin Blake was Head of the Illustration Department at the Royal College of Art from 1978 to 1986. His latest books are, with John Yeoman, The Do It Yourself House that Jack Built (Hamish Hamilton), and The Quentin Blake Book of Nonsense Verse (Viking).