Lady Diana Cooper, who took a keen interest in both men, once remarked that whereas Evelyn Waugh was “a bad man for whom an angel was struggling”, his fellow Catholic convert Graham Greene was “a good man possessed of a devil”.

While Waugh’s visit to late-1930s Mexico produced a deeply conservative political tract (Robbery Under Law, 1939), his friend returned with the material for a novel. Yet, as Nick Warburton’s superlative two-part adaptation of The Power and the Glory [19 and 26 June] demonstrated in spades, Greene’s fiction turns out to be quite as polemical as Waugh’s bitter travelogue.