I have now exhausted the resources of the South West Libraries (well, all bar one final book which is still on order). The Golden Age has been reasonably well-served with 11 of the 34 recommended titles (if we exclude the ones I have already on my own bookshelves) in stock – either on the shelves or stashed away in some vault somewhere to be retrieved on request.

The last three I have read – Traitor’s Purse and Hide My Eyes, both by Margery Allingham and The Water Room by Christopher Fowler are all published later than the traditionally accepted Golden Age of between the wars and all show developments from the classics of the genre.

Traitor’s Purse has the detective, Albert Campion, suffering from amnesia which places him in the same situation as the reader – not knowing what is going on and having to figure it out for himself as he goes along.  An interesting twist to see him struggle rather than exhibit the more usual omniscient brilliance of the insightful detective.

If Traitor’s Purse has Campion cast in the role of central protagonist in an almost 39 Steps like nod to the heroes of the thriller genre, given it was a wartime publication,  then in Hide My Eyes, he is almost relegated to the background as others carry the bulk of the action (arguably the book need not have been a Campion novel at all and could have been managed without his presence).

It is possible to read The Water Room as a critique of the police procedural which superseded the Golden Age style. The Peculiar Crimes Unit (the title says it all) which carries out the investigation is placed neatly outside the control of the Metropolitan Police and follows the accepted modern procedures or not, more or less as the author fancies. In this way it almost harks back to the earlier era.

Yet all three still adhere, more or less, to the rules expounded by Ronald Knox in his introduction to Best Detective Stories 1928-29, which I paraphrase below:

1. The criminal must be a person introduced near the start of the story and be someone whose full thoughts the reader has not been allowed to follow.
2. No supernatural solutions are allowed.
3. No more than one secret room/passage is allowed.
4. No hitherto unknown poisons are to be used (nor any complex scientific gadget requiring tedious explanations).
5. No stereotypical (my italicised insertion) Chinese person should feature (see previous article on implicit racism pervading the genre because it reflected contemporary society norms).
6. No accident must help the detective to solve the crime, nor may he reach the solution by unsupported intuitive (i.e. guessing it correctly) rather than deductive methods.
7. The detective must not commit the crime.
8. The detective must not rely on clues that are concealed from the reader.
9. The detective’s sidekick, if present, should be ever so slightly dimmer than the readership.
10. Identical twins shall not feature in the solution unless clearly flagged beforehand.

Of course all the great authors of the Golden Age felt free to break one or more of these rules when it suited them – we can all think of examples that are classics of the genre which do so – but when they did, it was very deliberately and for a good reason.