Over the decades Dahl's productivity grew and grew, like the giant peach that had started it all. For him there was no magic powder, just the regular couple of hours every morning and afternoon spent in his hut. Whilst the 1970s saw a balance of adult short stories and children's books, by the 1980s Dahl was writing almost exclusively for children, producing some of his best-loved work, including The Twits, George's Marvellous Medicine, The BFG, The Witches and Matilda.

‘In my little work hut I enter a dreamlike state,’ he explained to me, ‘sinking back into childhood. I really have a six- or seven-year-old's mind in this ancient body.’ He grimaced as he tried to get comfortable on the pillows. ‘I have ideas swirling around in my head throughout the day, in the bath, out in the garden, everywhere. The only time I am not dreaming is when I go up to my club in London to gamble – blackjack. You have to concentrate then. That's why I go; takes my mind off the work. I can't manage more than two hours writing at a time. I don't think you can focus, and anyway my back couldn't stand it.’

Although Dahl had suffered severe facial and head wounds in the plane crash, it was the back injuries that caused him lifelong problems. ‘An irregular, short-long, short-long limping gait which reminded one somehow of the swing of a maladjusted pendulum …’ Dahl could have been writing about himself, when he described a fictional RAF pilot in his adult novel Some Time Never:A Fable for Supermen, published in 1948. This futuristic book was notable for being the first ever novel about nuclear war, and included some extraordinary descriptions of biological warfare. However, it was not well-received by the critics and Dahl rarely spoke about it.

By 1944, four years after the crash, Dahl was ‘hobbling … like an old man’ and had the first of many back operations. He was living in America at the time and his wealthy friend Charles Marsh paid for the removal of an intervertebral disc.