FOR a 50-year-old, it must be said that Miffy the little rabbit is still looking pretty good.

Same un-marked white skin, crosshatched nose, quizzical dotted eyes. For a characterwho has crossed into 40 languages and sold some 85 million copies, she is remarkably unscathed by the years. Perhaps this is because Miffy is still drawn and tightly controlled by her original creator, the 78-year-old Dutch designer Dick Bruna. Perhaps because as Happy Birthday Miffy, a celebratory exhibition that opens at Motherwell Heritage Centre tomorrow, amply demonstrates she was such a well-constructed little rabbit in the first place.

Precise, but not machine-tooled, hand-drawn to a rigid formula with a limited colour palette of black, red, blue and green, she is more a pictogram or a calligraphic mark than a traditional illustration.

Born on a wet and windy seaside holiday in North Holland in 1955, Miffy came into the world when Bruna was attempting to entertain his one-year-old son. By 1963, she was definitively female - Bruna thought that dresses were more interesting to draw than trousers.

By 1964 she was a star in Japan and, through a subtly evolving process of change, a year later she was more child than toy rabbit. In many ways, Miffy is a key part of the baby-boomer generation. Her PR machine is keen to point out that she shares the year of her birth with, among others, Bill Gates and Bruce Willis. But she is also eternally youthful and appealing.

Happy Birthday Miffy is far more than a plot to extract cash from the parental wallet. Put together by Seven Stories, the National Centre for Children's Books based in Newcastle and cleverly curated by Gillian Rennie, this show had nearly 26,000 visitors on its Tyneside leg.

This is an exhibition designed to satisfy both adults and children.

Interactive demonstrations for kids are a key part of the construction, but alongside these are texts aimed at adults to ensure that design aficionados and curious carers will have as much pleasure as early learners, as long as they can put up with the inevitable over-excitement on the part of younger visitors.

The show's themes range from the sophisticated - "Showing Emotion", for example captures both Bruna's skill at evoking feelings from infinitesimal movements of line as well as helping children explore issues like sadness, loss and joy - to the plain fun: who would turn down the chance to attend "Miffy's Birthday Party"with its indestructible cake? AMiffy Post Office cleverly weaves the theme of letter writing - Miffy has a regular correspondence with her friend Melanie - with Bruna's own work designing stamps for both the Netherlands and Japan.

There is a Miffy Library and a Miffy Garden, each exploring different aspects of Bruna's art.

Bruna, it must be said, is one of the truly great graphic designers. He drew as a child, and in hiding in the countryside during the war, art became an important respite. The exhibition shows how his early drawing became gradually more and more pared down, more graphic and punchier. His compulsion to draw is charmingly illustrated by the sketches he made on his honeymoon of a bowl of fruit and a hotel clotheshorse.

Bruna was born into a publishing family, but by rejecting the business side of things he became a celebrated in-house designer. As well as inheriting strong Dutch design principals via the De Stijl movement of Piet Mondrian and Theo van Doesburg, on a visit to Paris in the early 1950s, his head was turned by the work of artists like Chagall, Dufy and Leger.

Before Miffy, his most successful workwas for the Black Bear pocketbook series, designing classic book jackets and railway posters for thrillerwriters like Simenon, Charteris and Ian Fleming. In these bold, iconographic images we can see the roots of Miffy. Each author has a recurring symbolic image, a pipe for Simenon for example and the Black Bear logo itself has a childlike appeal, not unlike the British Penguin imprint. By the series's maturity in the 1960s, no type was required; a poster showing a bear reading a bookwas sufficient advert enough.

This minimalism is what characterises Miffy; no surplus information, no added colours or unnecessary backgrounds, but it shouldn't be mistaken formere formula. A sequence dedicated to Bruna's working methods shows how painstakingly each illustration is made, often from hundreds of images.

If this all sounds rather gushing, don't take it just from me. When Bruna visited the Edinburgh Book Festival in 2000, grown artists were seen to quake with pleasure as much as small children. Hey, even Picasso was reputedly a fan of the little white rabbit. No wonder she has lasted so well.

Happy Birthday Miffy, is at Motherwell Heritage Centre, from tomorrow until October 3.

Wednesday to Saturday 10am to 5pm, Thursday until 7pm, Sunday from noon to 5pm. Closed Mondays and Tuesdays.

Admission is free.