Once upon a time there was an author who loved grandparents. Who can forget the valiant Norwegian grandma who fought off The Witches, or dear old Grandpa Joe in Charlie and the Chocolate Factory? They weren't always good - think of the grizzly, grumpy granny of George's Marvellous Medicine, with her small puckered-up mouth like a dog's bottom. Good, bad or ugly, Roald Dahl wrote unforgettable older characters.

Anne Lamott said in Some Assembly Required: "Kids are hard - they drive you crazy and break your heart - whereas grandchildren make you feel great about life, and yourself, and your ability to love someone unconditionally, finally, after all these years." The bond between grandparents and grandchildren has inspired many unforgettable stories and characters, like eccentric Grandpa Potts in Chitty Chitty Bang Bang, or wonderful, magical Grandpa Chatterji.

So why is it less easy to come up with adult books which feature grandparents as main characters? Surely there's a ready audience for books which reflect the experiences of the older reader? Perhaps the runaway success of Hilary Boyd's Thursdays in the Park is indicative of this, (and interestingly the huge e-book sales show how many older readers have adopted the digital format). This tender, wryly humorous family story about the late-in-life love affair between Jeanie and Ray has its finger on the pulse too - while divorce rates are falling in general, they are rising among the over 60s.

Deborah Moggach is another author whose books about OAPs appeal to a wide audience. These Foolish Things about outsourcing pensioners to India was adapted into film as The Best Exotic Marigold Hotel, and proved so successful there's now a Second Best. There is a new wave of hit films featuring grandparents, from Quartet to Song for Marion, starring Vanessa Redgrave and Terence Stamp.

Often when I'm looking for inspiration for my novels, I pinboard images of older actors. I love writing multi-generational stories, and the grandparents with their experience and wisdom frequently teach the younger characters an important lesson. Although, as Tove Jansson pointed out in her gorgeous recent story The Summer Book about a grandmother and granddaughter, sometimes the grandparents behave just as badly as the children. The grandmother reflects: "Wise as she was, she realised that people can postpone their rebellious phases until they're eighty-five years old, and she decided to keep an eye on herself."

The work of Latin American writers like Gabriel Garcia Marquez and Isabel Allende are among the finest examples of multi-generational story telling. From Marquez's artist, soldier and father of seventeen sons, Colonel Aureliano Buendia, to Allende's Esteban Trueba and Clara del Valle in The House of the Spirits, the older characters are richly drawn and centre stage. Allende's characters were inspired by her own grandparents. As she said: "with relatives like mine, I don't even need to use my imagination".

Perhaps the time is right for a new generation of literature, one where grandparents have as important a role as they do in other creative forums. In television, multi-generational programmes have always been popular, from Dallas and Dynasty to the Waltons and Modern Family. Maybe now is the time to see more mature characters in fiction. These are the family stories to be written, where retirement is simply the next chapter, not the conclusion.

Kate's new novel The Christmas We Met is published by Orion and available from Amazon.