‘So why do detectives have really odd names?’ The OH asked me as I wrestled with the first draft of Lukas Mahler’s next outing.

‘They don’t.’

‘A lot of them do.’ He reeled off a long list, starting with Sexton Blake and ending with J K Rowling’s Cormoran Strike. ‘Even Sherlock Holmes is a bit strange, when you think about it. Is it to make sure you remember them?’

Hmm. Had to admit, he’d got a point. Even allowing for late Victorian naming conventions, Sherlock and Mycroft are slightly off-the-wall choices for what are, ostensibly, the good guys. And it’s a trend that seems to have continued through the decades: Endeavour Morse. Horatio Caine (CSI Miami). Kinsey Milhone – even John Rebus, Edinburgh’s finest (in the eyes of his fans, though probably not his superiors) – they range from the somewhat unusual to the distinctly ‘huh?’.

And yes, I do think making sure their names stayed in your head once the book/film/TV is over probably played some part in the authors’ selections, even if only on a subconscious level. Making your ‘tec memorable is a sine qua non of the crime fiction world, and giving them a name that sticks surely doesn’t hurt in that regard. But that’s only part of the answer – as in all genres, the best, most enduring protagonists have a mix of character traits that make them compulsive reading/viewing.

What I suspect the unusual name helps to do is underline the idea of the detective as the outsider. Whether they’re working in a team or as the traditional ‘lone wolf’, the detective always has to keep some part of themselves detached, as an observer, an examiner of the players in the story enfolding in front of them.

Sometimes, like Poirot, this apartness is made very clear – in his dress, his speech, his habits, Poirot is the eternal outsider. At other times, like Matthew Shardlake, CJ Sansom’s masterful creation of a hunchback lawyer in Tudor times, the ‘otherness’ manifests in physical deformity. And placing Lukas Mahler, my Scots-born, half-German DI in Inverness’ Major Investigation Team … poor Lukas, I couldn’t have made him any more of an outsider if I’d given him a public school education and sent him to Cambridge. Oh, wait…

And maybe in the end, that’s why so many writers have a special fondness for our detectives, whether they come with … interesting … monikers or not. Outsider. Observer. Examiner of other people’s behaviour.

Sounds a lot like us really, doesn’t it?