Now she has turned her bold enjoyment of fantasy to a young adult readership. The Rainbow Opera, her latest book and the first part of "The Dreamhunter Duet", employs a geographic shift into a parallel world similar to the portal in Black Oxen. From a lush New Zealand-like country, a privileged few are able to walk along a pathway straight into a hidden landscape, simply called "The Place". Once there, even fewer are able to harvest dreams in this barren other world; they return to broadcast them to a paying audience in special sleeping auditoria such as the elaborate Rainbow Opera itself. Most dreams seem benign - but Laura Hame, the novel's determined, adolescent protagonist (and daughter of the man who first discovered The Place's existence), begins to pick up nightmares that have profoundly disturbing implications for the fabric of her native society.
"I like fantasy for some deep aesthetic reason," Knox explains, "but I also like it because it provides a way of dealing with the awe and the terror without actually tying down these experiences to things that everybody recognises - so you are actually processing the emotional experience of awe or terror itself. This is particularly true of young adult books."
Writing for a younger readership proved a very different discipline for Knox. Her habit of compressing subtle character nuances into slabs of reported speech was ditched in favour of direct dialogue, which she loves writing. "My principle was to be as clear as I could be about the feelings of the characters, so that the reader could feel as close to them as possible. There must be very little distance between the reader and the protagonist. The reader always has to know what they are feeling. You basically say what your characters are going through, emotionally." She was greatly assisted by a critical reader: her 12-year-old son, with whom she discussed intensely the work-in-progress. "He told me if he got fed up with things."
Did her family critic make her think adolescents were generally a more unforgiving readership? "I think they have fewer expectations about how certain books should be," she replies evenly. "They haven't read as many books as adult readers, and so perhaps they are more patient about not being able to see where things are going. Young readers are used to not necessarily being able to follow everything all at once."
I idly wonder if this is a tacit admission that novels written for adolescent readers require less substance or gravity, but quickly regret the suggestion. There is no lack of moral complexity in the writers she admires, such as Philip Pullman or Diana Wynne Jones. "The Rainbow Opera is a coming of age story," Knox allows, as most writing for young adults tends to be; but that doesn't mean that the problems confronted are less substantial. "In the very best young adult books there is as much going on as in adult literary fiction," Knox claims, adding with a modest laugh that "what gets classed as adult literary fiction is sometimes just polite noises."
To buy a copy of 'The Rainbow Opera' (Faber £9.99) with free p&p, contact Independent Books Direct on 08700 798 897