JR Moehringer, biographer to stars such as Andre Agassi and a doyen of the genre, was an obvious choice for the Duke of Sussex

When Prince Harry chose to work with ghostwriter JR Moehringer on his institution-shaking memoir, Spare, he was not taking half measures. The American writer and Pulitzer prize-winning journalist does not have a huge output, but he is known for his immersive approach to subjects, his preoccupation with the father-son relationship, and his capacity to “go deep”.

When he worked with Andre Agassi on ghostwriting his celebrated 2009 memoir Open, the tennis star said Moehringer moved to Las Vegas and bought a house a mile away, where he lived for two years. They would meet in the mornings over Whole Foods breakfast burritos, Agassi said.