Anne was born 20 minutes after Janet on 1 June 1928. Their mother was Doris Zinkeisen, a successful portrait painter and stage designer, who did valuable work for the Old Vic during the Second World War. In 1946 the twins' father died; both girls then lived with their mother for the rest of her life (she died in 1991).
After studying at St Martin's School of Art, they settled down as professional illustrators, staying in London until 1966 when they finally moved to Suffolk. They worked on every picture together, passing illustrations between each other until both were satisfied. Janet, the more assertive of the two, concentrated on animals while Anne was the expert on period costume. Early commissions included Enid Blyton's Tales of Ancient Greece (1951), and new illustrations for that hoary old shocker Struwwelpeter (1950): a bizarre enterprise which must now surely be a collector's piece.
But most work was done designing Christmas cards and illustrating numbers of large, brightly coloured gift books, mainly published by Dean. Their full-page illustrations surrounding nursery rhymes, fairy tales or children's prayers were in the tradition of undemanding effusiveness set by older artists like Hilda Boswell, still hugely popular with the public though increasingly frowned on by critics.
Conservative by nature, the twins were never artistically innovative, but their best work away from the demands of gross commercialism could still be very good indeed. This is evident in their drawings for Dodie Smith's The Hundred and One Dalmatians in 1956. The old-fashioned frontispiece illustrating "The Twilight Barking" with its atmospheric use of shadow, fine detail and number of different habitations brilliantly set the tone for what was to come. Here were pictures for children to pore over: meticulously executed Tudor mansions, bricked-up Georgian facades, four-poster beds and deserted follies all making an intriguing backdrop for the heroic dog characters.
Far from gazing winsomely at their readers, these animals are shown as alert and business-like. Clever angles and some unexpected perspectives anticipate Disney's cartoon film to follow. As with Edward Ardizzone, human characters are often pictured from the back but still come over in a strongly individualistic way. The only failure is Cruella de Vil, almost defiantly un- evil-looking in tune with the twins' own essentially benign outlook on life.
In 1979 Janet died in an accident. Although devastated by this loss (their brother Murray described them together as one and a half rather than two people), Anne found the strength to honour all their existing commissions and to continue alone. She learned how to draw the animals that Janet used to specialise in, becoming so adept that she was this year elected a Member of the Society of Equestrian Artists.
This fascination with horses did not end there; the twins had previously driven a smart dogcart around the Suffolk countryside, with Janet holding the reins and Anne dealing with the whipping. After Janet's death Anne continued this hobby, winning numbers of cups and rosettes at various competitions.
Never a particularly spiritual person - her Little Jesus Pop-up Book (1976) owed more to paying the bills than religious fervour - Anne nevertheless accepted the fact of the liver cancer that was to kill her with courage and grace. Always more concerned for others than for herself, she continued to work until two days before her death.
Like her sister, Janet, Anne Grahame-Johnstone never married, but enjoyed close relations with her nephew and two nieces, all of whom work in the arts. Her legacy to children everywhere includes work on Andy Pandy and the Flower Pot Men in early children's television, and numbers of Christmas jigsaw puzzle designs. But she and Janet will chiefly be remembered for their huge output of illustrations stretching from Peter Pan to Gilbert and Sullivan, always executed to a high professional standard and at best, in the line drawings, able to compete with some of the finest work of their generation.
Anne Grahame Johnstone, illustrator: born London 1 June 1928; died Badingham, Suffolk 25 May 1998.