This fictionalised telling recounts an episode from the life of Sir Robert Watson-Watt. Based on diaries and letters, the substantial facts are true, while some of the connective tissue is a work of imagination. Intriguingly, given how their lives were to criss-cross, it shows that, like Dame Katherine, Watson-Watt knew all about ‘spycalists’, not least because, rather improbably, he was one himself. You can read it in its entirety here.