The spies who came back rather old

In John le Carré's most famous books, the Berlin Wall is as significant a feature as the portly old spy George Smiley. The Spy Who Came in from the Cold (1963), the novel which made Le Carré's name (Graham Greene called it "the best spy story I have ever read") begins and ends at the Wall: in between it delivers a narrative that never loses its power to shock. Alec Leamas, a burned-out agent, and his unwitting girlfriend Liz Gold, a young British communist, are caught up in a mission that, it turns out, requires their ignorance. Leamas thinks he is bringing down Mundt, a former Nazi in the East German secret service; but Mundt is already working for the British, and the real target is Fiedler, a man who might expose him:

"All right!", Leamas shouted suddenly. "I'll tell you what you were never, never to know, neither you nor I. Listen: Mundt is London's man, their agent; they bought him when he was in England. We are witnessing the lousy end to a filthy, lousy operation to save Mundt's skin. To save him from a clever little Jew in his own department who had begun to suspect the truth. They made us kill him, do you see, till you know, and God help us both."

Leamas and Gold are supposed to escape but Mundt smartly has them shot as they try to cross the Wall. The degree of British collusion in that decision is left ambiguous.

Throughout the Cold War novels that followed, with the Karla trilogy (Tinker Tailor Soldier Spy, 1974, The Honourable Schoolboy, 1977, and Smiley's People, 1979) at their apex, we see a pattern: heroes founder because of humane or romantic impulses and values which are then used against them: the very impulses and values that the Western spies are ostensibly fighting to protect. The arguments over ends and means re-occur in every book. This is why even the victories in Le Carré feel like moral defeats, just as some of the defeats feel like moral victories. His real heroes are trying to find a path between the self-serving bureaucrats and politicians on their own side and the ideological enemy on the other; there is in that regard a touch of Rudyard Kipling to Le Carré. When at the end of Smiley's People, Karla, Smiley's old foe, is forced to defect, the final scene occurs, of course, at the Wall.

"George, you won."

"Did I?" said Smiley. "Yes. Yes, well I suppose I did."

It is arguable that Le Carré has struggled a little since the Wall came down. The style has remained the same: laconic, deft descriptions and character sketches, like witty surveillance reports; the drama of interrogations ("listening by habit for the tiny flaws and the chance discrepancies and the omissions and the change of emphasis", as described in Smiley's People), where variations in tone carry vast dramatic weight; the very occasional deadpan account of real and terrible violence. And the types have remained the same – boys literally or figuratively orphaned searching for father figures or for damsels in distress, wrecked by their better natures and ultimately outplayed by darker, more cynical figures. Only the enemy has changed – arms dealers, Big Pharma, the CIA – and the tone has become a little more strident, the moral terrain less ambiguous.

So it is understandable that Le Carré, now in his mid-eighties, should revisit the scene of his greatest triumphs and his finest creation, George Smiley. A Legacy of Spies is narrated by Peter Guillam, Smiley's ally throughout the Berlin Wall novels, also now in his eighties and dragged from retirement in rural France to be interrogated by harsh young professionals in London – Bunny, "a fresh-faced, bespectacled English public schoolboy of indeterminate age" (a familiar Le Carré type) and Laura, "an aggressive lawyer of indeterminate sexuality", who represents "History" ("History as an expressionless woman with short hair, brown eyes and no make-up"). Guillam is being called to account for the events of The Spy Who Came in from the Cold, the deaths of Leamas and Gold, the killing of the Jew to save the Nazi. (He also seems to be being punished for a lifetime of sexual promiscuity, and for inappropriate relations with agents.) As he is led, forty-five years on, through what evidence remains, a sort of prequel to Spy emerges.

Guillam is told that Alec Leamas had an illegitimate son, now in his sixties and seeking recompense for the way in which his father was sacrificed. And Liz Gold apparently had a daughter from her teenage years, hushed up and adopted. She is also party to the lawsuit. One character describes this as a "ludicrous Shakespearean premise", which rather dignifies it. Beneath some strained philosophical worrying ("who will atone for our father's sins, even if they weren't sins at the time?") the book seems mostly set on a nostalgic outing for some of Le Carré's best-loved characters and plotlines. This means it will primarily be of interest to his most loyal readers.

Which raises the question: why are there so many discrepancies between the earlier books and this one? Alec Leamas, in fact, already had children ("somewhere long ago there had been a divorce; somewhere there were children, now in their teens"; "Leamas has got two children by his marriage, did you know?"). That Gold should have a daughter is possible, but barely credible. In the replay of events from Spy, there are pointless variations, some minor (after the initial contact from Dr Riemeck to the de Jong family, does Leamas offer $500 "regularly each week" as in Legacy, or $1,000 twice in the next six weeks, as in Spy? Does he leave a number in a "child's colouring book" or a "children's science fiction book"?), some more significant. There is no suggestion in Spy that Leamas ever attends a Communist Party Open Day with Gold: "No one knew [about us]", she says.

In Legacy, there is a Special Branch report of a meeting attended, as a couple, by Leamas and Gold. (We read that "regular attendees include members of the Socialist Workers' Party, 'Militant', the Campaign for Nuclear Disarmament" – though the SWP didn't get that name until 1977, and Militant didn't start until 1964.) The subsequent assault of a credit-refusing grocer is also radically different between the books; for example, two clean blows in Spy, becomes a "rapid succession" to stomach, groin and face in Legacy; the value of the disputed goods in Spy was less than a pound, but in Legacy it has become a remarkable £45 – many hundreds in today's money.

Why introduce Connie Sachs in Legacy? In the Karla trilogy, this doyenne of the Circus is old, arthritic, drunk and out to grass; after all, she'd been recruited as a debutante in the late 1930s, over a game of bridge. So it's a shock to find her "in her early twenties" in the early 1960s; and more of a shock, then, that this new young Connie could have been suspected of being a double agent in 1959 by a paranoid Leamas, when – "wunderkind" or not – she'd have presumably been in her teens. (That paranoia, by the way, is grafted back onto the Spy narrative to anticipate the mole hunt in Tinker Tailor Soldier Spy – again, unnecessarily, and again aimed at the very readers who will spot these variations.) These are the only references to Sachs, negligible, en passant; she plays no role. So why drop her in as a woman of a different age? Millie McCraig is given retrospective youth as well, but otherwise she'd be in no state to appear in this book.

But those minor details (and that was not an exhaustive list, alas) are as nothing to what has been done to poor Peter Guillam. His age is at least consistent with the earlier novels (with the exception of the very first one, Call for the Dead, 1961, after which Le Carré revised everyone's chronology); but his parentage is now in dispute. In the early books "His father, a French businessman, had spied . . . in the war, while his mother, an Englishwoman, did mysterious things with codes". In Legacy his father is "the wastrel son of a wealthy Anglo-French family from the English midlands" and his mother is "sole offspring of a long line of Breton farmers".

Guillam now has hearing aids, though it's not clear he needs them; and even in his eighties, his tradecraft is as good as ever, not to mention his readiness for a scrap ("I'm wondering if I'll get the chance to grapple with him and in the worst case shove him at an oncoming car"). But the matter of age does make the few contemporary events of Legacy faintly bathetic. The final encounter between Leamas's son Christoph and Guillam is between pensioners still acting and talking like young men; the eventual emergence of Smiley, born in 1916 at the latest and therefore around a hundred now, also fails to ring true: "it was the same George, just grown into the age he had always seemed to be."

Philosophically, A Legacy of Spies dwells, not wholly convincingly, less on the question of whether the end justified the means at the time than on whether subsequent events have made the whole struggle, with all its damaged lives, pointless in retrospect. In late Le Carré there has been a tendency towards unambiguous polemic (Absolute Friends being a striking example). Here we are more in the interesting territory of moral uncertainty and failure. What, Smiley asks, was he fighting for? Well, after ruling out world peace, capitalism and Christendom, we end up with England. "But whose England? Which England? England alone, a citizen of nowhere? I'm a European, Peter . . .". The phrase "a citizen of nowhere" is not idly chosen. George Smiley, the expert on medieval German poetry, the doughty fighter of losing battles, has, of course, come out for Remain.