With a drama series that deals with terrorism and anarchy, the BBC seems to be attempting to upset the cosy conventions of Sunday night television. But at the same time, its adaptation of The Secret Agent (from 17 July) retained the surface attributes of the Victorian costume drama: street urchins, women in aprons and a steam train or two.

Joseph Conrad’s novel did very poorly during the author’s lifetime, but it is now rightly recognised as one of his most important works. This is due not least to its remarkably prescient interest in the workings of extremist political cells. Tony Marchant’s admirable adaptation kept to the essentials of the novel’s plot, introducing us at the start to Verloc, a somewhat ineffectual spy for the Russian embassy and sometime informant of the Metropolitan Police.

As Verloc, proprietor of a Soho dirty-goods emporium, Toby Jones gave us another of his celebrated exercises in bafflement and anguish. We saw him threatened by the Russians and blackmailed into a bizarre plot to blow up Greenwich Observatory. The first secretary of the Russian Embassy explained the rationale: the action was to be “sheer incomprehensible random madness, without regard to limits or sense”. He promised the horrified Verloc that the attack need not be “sanguinary”.