Her novels cover the great themes of human existence - love, betrayal, race, slavery. Margaret Atwood calls her one of the pre-eminent American novelists of all time; Chinua Achebe praises her courage for asking the most haunting questions in black history. She is studied in schools and universities across the US and is that rare thing in the literary world: both critically acclaimed and read by millions.

Today, though, Toni Morrison wants to talk about her hip: "I've been walking like the hunchback of Notre Dame," says the 77-year-old in her soft, deep voice. "Thing is, I'm a total shoe freak, I buy them everywhere." For lunch she is wearing flats with black trousers and top - adding a dash of glitz with a string of giant pearls and a sparkly silver band that holds back her loose grey plait. But she'll soon be out dancing in heels again: "My doctor said so," she says, and her laughter rings out across the room.