Agatha Christie famously once commented that, had she foreseen the lasting popularity of Hercule Poirot, she would not have made him a man already in mid-life in the book marking his first appearance – and the beginning of Christie's own literary career –, The Mysterious Affair at Styles (1920). The awkwardness of that situation, from the writer's point of view, would come to be even greater in the case of Miss Marple, who even at her first appearance in 1930's Murder at the Vicarage was already an elderly lady; a character partly inspired by Christie's own grandmother. Maybe Ruth Rendell should have heeded that thought when she was writing From Doon With Death, the 1964 novel which, in turn, marked both her own literary debut and Inspector Reginald Wexford's first appearance. For Wexford, too, came to his readers ready-made as a Detective Chief Inspector; i.e., a police officer of advanced rank and a corresponding degree of maturity. Yet, as in the case of Agatha Christie's famous detectives, readers did not seem overly bothered by the fact that over the course of the decades Wexford did not age in real time, and indeed, he at least did age more noticeably than Hercule Poirot and Miss Marple, both of whom remained essentially unchanged even as the world around them changed a great deal. Rendell's career as a writer thrived on the basis of the Wexford novels as much as it did on the basis of her stand-alone mysteries and thrillers, many of the latter published under the pen name Barbara Vine. British TV also went on to produce a long-running TV series, starring George Baker as Wexford and Christopher Ravenscroft as his sidekick, Inspector Mike Burden; in both actors' cases, arguably still the roles for which they are the most widely known.
Eventually, however, retirement is bound to catch up even with a fictional detective of Wexford's staying power. Already at the publication of the 2009 mystery The Monster in the Box, an interview given by Rendell herself fostered the notion that this was going to be her last Wexford book. That turned out to be wrong, or in any event Rendell changed her mind; however, in the follow-up novel The Vault, Wexford had retired. No Man's Nightingale (2013) is the second novel in which Wexford is consulted by Burden, now his successor and himself a Detective Superintendent, in connection with a murder case, and brought in as an unpaid so-called Crime Solutions Adviser (whatever precisely that may be).
Preview also cross-posted on Leafmarks.