The economics of a sex club have somehow evaded my attention. Adam Smith doesn’t touch on the subject, and the dreary wastes of the screeds of economic historians on the period I know best cover much but not prostitution let alone sex clubs. So I was unsure about the economics that underlay the excitement in my first choice; but maybe the possibility of blackmail helps. Cover the investment? Did Private Equity stretch to these ends? I must ask x; no lips are sealed.

John Dickson Carr’s Paris novels are quite different to the norm of interwar detective fiction, thus indicating its inherent variety. Agatha Christie set episodes in Paris, and notably so in The Mystery of the Blue Train and The Big Four, while Paris also crops up for example in Lord Edgware Dies, a novel that fascinated me as a small child as I was born in Edgware. Well Agatha’s Paris has a strong current of violence but not the sexual tension and sensual wildness that Carr relished. With all the vim and daring of a young man, and he was 25 at the time of writing The Corpse in the Waxworks: A Paris Mystery, he offered not only the mysterious and deadly subterranean wax works but also a nearby sex club, the Club of Coloured Masks, in the Boulevard de Sebastopol.

There are 50 men and 50 women in the club, all from the height of society, and making assignations accordingly, with the colour of the mask indicating their quest as it were. At risk to his life, because the club is well-protected by white-masked knifemen, our hero penetrates the club in order to eavesdrop on a murderer, and this is certainly not St Mary Mead. As with other Carr novels, I am amazed by the energy expected from the participants in what is a very compressed timetable. The twists and turns of the plot work well, and, if I was not convinced about the murderer, I admired a pace and style that grabs you fast. Carr likes arresting phrases such as “a wind rattled shrewdly at the awning”, but it is his settings that are dramatic, and repeatedly so. I did not like The Lost Gallows or Castle Skull in this series, but, in this book, his approach works, and charges you along. As a digestif, the book includes “The Murder in Number Four”, a short story again featuring Henri Bencolin, the head of the Paris police, in this case solving an impossible train murder.

A very different tone and setting are offered by Freeman Wills Croft in The Hog’s Back Mystery (1933), which I read many years ago and now welcome in a fine British Crime Classics version. Inspector French is very much steady as he goes. Croft describes French as acting in “his painstaking way”, and has French refer to himself as “slow … but terribly sure”. The detective is described as very steady, as in “Having fortified himself with a cup of tea – it was just five o’clock – French reached the police station” or “He and his wife remained as good pals as ever they had been.” As with other elements, the details of detection are handled with deliberation: “Breakfast was becoming quite a problem. He didn’t want to take the time necessary to go into Farnham for it, but he knew that when he grew hungry the quality of his work fell off. On the other hand, he did not like to ask for anything in a house in which he was a potential enemy.” Not the most stimulating, but if you like a steady-as-it-goes murder story that proceeds in a systematic fashion, this is an excellent example of the genre. The characters are ably sketched and, amidst all the cigarette smoke, there are some satisfying twists. Calms one down after Carr.

The Female Detective by Andrew Forrester (a pseudonym for James Redding Ware), presented to readers in 1864 the first professional female detective, although her history and character were not really sketched in. British Crime Classics published this in 2017 and it remains in print at £8.99. This is a reprint of the 1864 work with a useful introduction by Mike Ashley. Essentially a collection of short stories, the work will please in parts and is certainly worth reading by those interested in the genre and for the light it throws on Victorian society, not least family inheritance tensions.

Jeremy has recently published Britain 1851-2021.