Melvyn Bragg is best known as the presenter of long-running TV arts programme the South Bank Show. But he is also a prolific writer, and has just published his 21st novel, Grace and Mary.

It tells the story of 71-year-old writer John, who regularly visits his ageing mother Mary in her nursing home, where she is falling victim to dementia. Hoping to shore up her memory, he prompts her with photographs and questions about the 1940s, when she was a young woman. But he finds that most of all it is her own mother she longs for – Grace, a woman she barely knew.

John sets out to recreate their buried family history, delving into the secrets and silences of Mary’s fractured childhood as he imagines the life of her spirited mother.

The story is set in Cumbrian-born Melvyn’s home county, and he admits that the novel is strongly autobiographical, drawing on his relationship with his late mother Mary, who had dementia, and her experience growing up with foster parents after being born illegitimately to a woman called Belle.

In Melvyn’s novel, his mother becomes the fictional Mary; Belle becomes Grace.

The 73-year-old said: “I have been writing autobiographical-based fiction for a long time. You may be drawing upon your own experiences but when you start to write, even when you’re writing about your own mother, it moves into fiction. And Grace is based on my grandmother who I never knew. She is completely invented.”

Although the novel’s themes, dementia and the social stigma of illegitimacy, may seem quite grim, Melvyn stresses the book is more of a celebration of female strength.

“They were two very spirited women who came through hard times. And although it is the dying of the light, dementia is not all terrible.”

He is looking forward to discussing the book’s themes with readers when he comes to Canterbury this weekend to sign copies at Waterstones.

And as is typical of the hard-working writer and broadcaster, he will also be fitting in a speech beforehand at The Gathering spiritual festival in the city.

At The Gathering he will be talking about 16th century scholar William Tyndale who translated the Bible into English. Tyndale was the subject of Melvyn’s 2011 non-fiction work Book of Books, and someone he describes in glowing terms.

“He’s the greatest Englishman in our history. His translation of the Bible affected everyone’s lives. He was the man who did it.”

And what better setting for his keynote speech than the heart of the Church of England, Canterbury Cathedral.

Melvyn said: “I have visited Canterbury many times before and always enjoy visiting the cathedral. I used to be a very strongly religious man, but now I would say I’m just interested in religion. You can’t not be. It has inspired so much of our culture.”

Melvyn Bragg will be signing copies of his new novel at Waterstones in St Margaret’s Street, Canterbury from noon to 1pm on Saturday, June 1. The hardback is priced £18.99.

He will giving his keynote address at The Gathering, titled William Tyndale: The Begetter Of The King James Bible And The English Language, at 11am on Saturday, June 1. Call 01227 787787 or visit www.the-gathering.co.uk