They do it with James Bond, so why not with George Smiley? The estate of Ian Fleming has allowed many new 007 books to be written by luminaries such as William Boyd, Anthony Horowitz and even Jeffery Deaver, to keep the franchise (and, perhaps, its copyrights) alive. So why not try the same with John le Carré’s great anti-Bond, the diffident, corpulent and brilliant spymaster of “the Circus”? At least here the literary pedigree is unimpeachable: the novelist Nick Harkaway is also le Carré’s son.

You wouldn’t want to plonk Smiley down in the present day and have him mutter owlishly about pronouns and smartphones. He belongs to the cold war, in his anonymous overcoats and ability to live in Chelsea. So Harkaway sets his story in a gap between canonical Smileys: after The Spy Who Came in from the Cold (published in 1963) and before the events of Tinker Tailor Soldier Spy (1974). (Smiley appears only in the background of The Looking-Glass War, 1965.) We are in 1963, to be precise, and the events recounted in The Spy Who Came in from the Cold are still fresh in the characters’ memories: they are all grieving for their colleague Alec Leamas, gunned down at the Berlin Wall.

What a treat it turns out to be to wander anew the fusty, crumbling warren of the Circus (not the peculiar open-plan brutalism of the 2011 Tinker Tailor movie). The original gang is all here: Control, with his spectacles that always catch the light just so, in order to make the lenses seem opaque; the fast-talking Hungarian hard man Toby Esterhase; Bill Haydon, the old-school charmer who will shag anything that moves; Jim Prideaux, the soldier-poet scalp-hunter; Peter Guillam, the sorcerer’s apprentice. They all act as aficionados would expect; the stentorian research queen Connie exclaims “It’s a song of sorrows, George”; while Harkaway has a lot of fun in particular with the speech patterns of Esterhase, who almost steals the show: “My God, this fellow. He’s making heavy weather, doesn’t want to play … You think we just bust him right now? Disgraceful conduct from a so-called diplomat, hobnobbing with professional assassins, we are all shocked, tell us everything or it’s persona non grata and no more Harrods.” Later, the reader is almost inclined to cheer when Esterhase explains, after a spot of fisticuffs: “I like to fly the flag for rootless cosmopolitans when I can.”

You ask about the plot? Well, Susanna Gero is a Hungarian émigré who works in the London offices of Mr Bánáti, a literary agent who every day “performed a series of ludicrous exercises devised by a Swiss”. One day her boss goes missing, and another man arrives at her door to explain that he was sent by the Russians to kill him but has changed his mind. There follows a satisfyingly slow and circumspect investigation by Smiley and team, followed by a similarly slow and circumspect chase across Europe. Berlin, Vienna, Budapest, Lisbon. The atmosphere is delicately painted in all the appropriate shades of grey.

The prose of Karla’s Choice is not an absolutely perfect exercise in ventriloquism of the master, nor does it try to be. There may be a few seeming anachronisms (we hear of old field agents who lack the “chops” for management; the word “definitionally” to mean “obviously” is overused), but there is a satisfyingly cold tone throughout, recalling the way that le Carré’s own furiously tamped-down moralism (in the novels of the 1960s and 70s, at least) could approach nihilism. (A doctor’s report on a man’s torture “noted with disapproval the unscientific use of lit cigarettes” on his legs.) Harkaway might be a smidgen warmer and more sentimental, but he is also funny in the right way: in Control’s office there is “an electric fire which seemed to generate only false expectation”. He demonstrates superbly, too, how suspense can arise from the patient accumulation of detail, and the brilliant climactic scene is nothing so vulgar as an action-movie shootout but rather a sequence of ordinary bureaucratic peril: the attempt to cross a border when one’s papers are not quite in order.

It cannot be a bad time to revive old George, what with a resurgent Russian threat (not so subtly adverted to herein) and the popularity of the TV series adapted from Mick Herron’s excellent Slow Horses books, starring the 2011 film Smiley, Gary Oldman. An afterword, mentioning the genesis of a wonderful new character, an expert Indian forger, or “artist”, hints that Harkaway might be planning more such stories. Well, le Carré once said that he didn’t write as many Smiley novels as he had planned because it was too hard to get away from Alec Guinness’s definitive portrayal in the classic 1970s TV adaptations. So at least we know we have the master’s blessing. And a drop more of his narrative voice’s caustic decency, expertly continued by Harkaway, would not go amiss in these times. “We don’t do justice, though, do we?” Peter Guillam remarks at one point. “That’s another department.”