Drink to Yesterday was based on the early life of one of its two collaborators, Cyril Henry Coles, who left school, lied about his age and enlisted as a teenager in the British army during World War I. He was transferred to intelligence when his remarkable aptitude for conversational German was noticed, and he became the youngest member of Britain's Foreign Intelligence Office (later MI6). Like Bill Saunders of the book, Coles spent much of the rest of war working behind enemy lines. Coles and his collaborator, a Hampshire neighbor, Adelaide Oke Manning, chose to cast his story in the form of the novel so as not to run afoul of the Official Secrets Act. Grimmer than later books in the series, it's also an ingenious circular story of murder, enlivened by the sardonic humor of Bill's mentor, Tommy Hambledon

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