In 1953, Ian Fleming’s novel Casino Royale introduced one of the most popular literary characters ever: the secret agent with the blue eyes, black hair and “cruel mouth”, the persistent appetites (for women, food and that special “shaken, not stirred” martini) and the immortal line “Bond, James Bond”.

By the time Fleming, a former journalist and naval intelligence officer, died on 12 August 1964 at the age of 56, he had written 14 James Bond books and established the basis for his estate to manage the franchise. Fleming’s 007 prototype has proven, indestructible, surviving through 23 films and also 24 additional novels written by six successive authors (not including the movie novelisations).

The James Bond books have had their ups and downs. Fleming was a shrewd and perceptive chronicler of a Cold War world much more dangerous than ordinary citizens understood it to be. He created Bond as a blunt instrument wielded by his superiors to preserve and protect. Fleming fleshed out his 007 with a flair for clothes and cars, a powerful athleticism and a fondness for women paired with a tragic inability to maintain love. When Fleming’s Bond was caught, as he always was, the villain made him suffer. Readers knew that at some point, however, Bond would always prevail. Fleming’s work was noir with a safe landing at the end. He wrote with a rare combination of clarity, action, sensuous detail, wit and fantasy.

Kingsley Amis, author of the first post-Ian Fleming 007 novel and the first critical appraisal, The James Bond Dossier, coined the still useful term “The Fleming effect”, which he describes as “the imaginative use of information, whereby the pervading fantastic nature of Bond’s world, as well as the temporary, local, fantastic elements in the story, are bolted down in some sort of reality”. Some of Fleming’s successors come up short when it comes to the crucial balance between imagination, authenticity and believability. Many are influenced as much by the film versions as by Fleming himself. Some have replaced Fleming’s Cold War plots with alternative wartime scenarios, to varying degrees of success. A few have lost the daring and witty Fleming flavour altogether. The most successful maintain his taut action style while adding psychological depth and a contemporary sense of humour.

Here’s my ranking of the six authors to carry on Fleming’s literary legacy:

6. Raymond Benson

Benson, author of the reference book The James Bond Bedside Companion (1984), wrote six Bond books between 1996 and 2002. He had two directives, he notes in the introduction to Choice of Weapons, a compendium of three of his 007 novels: “Make the character of M a woman (to stay in synchronization with the Pierce Brosnan/Judi Dench films), and to somehow blend more contemporary elements (more action, gadgetry, humor).”

Zero Minus Ten, Benson’s first novel, was set just before the British handover of Hong Kong to the People’s Republic of China in 1997. Bond ends up allied with the head of a Hong Kong triad in a race to keep the handover from becoming an explosive international disaster. Benson’s settings are effective, but he replaces Fleming’s pithy two-sentence backstories with pages of exposition that slow down the action. (Compare Benson’s 20-page scene covering the rules of Bond’s Macau mahjong game to Fleming’s four-page explanation of the game of baccarat in Casino Royale during a dinner followed by champagne, strawberries and avocado pear.) His Bond seems a hollow man, devoid of the animating sense of Bond’s actions that play such an important role in Fleming’s books.