Set in St Mary Mead, a quintessentially English village, this rural idyll is shown to be little more than a veneer as petty rivalries, whispered secrets and poisoned pens serve to divide the community.

Here Christie offers a biting reflection of the British class system, including a scathing critique of the Foreign Office, which she presents as a boys’ club of ‘purely ornamental’, upper-class chaps.

Anyone who has read the short story ‘The Plymouth Express’ would be forgiven for having a sense of déjà vu when embarking on The Mystery of the Blue Train.

There is a reason that Agatha Christie is celebrated for her country-house murder mysteries and not for her international espionage thrillers. While the former show her strength and originality as a writer, the latter can’t help but feel slightly derivative and, at times, a little absurd.

Christie’s forte is creating a web of intrigue on the domestic scale. Here her skills of observation, her ‘wonderful psychological insight into human nature’ (another quote from the present book) come to the fore.

The joy of The Secret of Chimneys emanates from its supporting cast – the witty and indefatigable Champagne socialist Lady Eileen Brent, the browbeaten Lord Caterham, the hapless Bill Eversleigh, even the overbearing, purple-faced politico George Lomax plays his part with aplomb.

In The Man in the Brown Suit Christie presents us with another plucky heroine, this time in the form of Anne Beddingfeld. Beddingfeld is one of Christie’s strong women, ready to weaponise her beauty and intellect, rather than subordinate herself to her patriarchal ‘protectors’.

The Murder on the Links contains a number of features that were to become Christie tropes – the watch with the broken face; the use of disguises; and the desire of a murderer to repeat their crime.

It is virtually impossible to describe The Secret Adversary without using the word ‘romp’, and it’s clear that Christie enjoyed writing this story.

Awash with red herrings and a cornucopia of clues, this book acts as a form of ‘preface’ to the stories that were to follow, introducing the reader to those elements that would become quintessentially Christie.