A series of spy adventures written in the 40s and 50s and set from WW1 onwards. I found this series by wandering around the books on Faded Page tagged with WW1, and have been inhaling them this week, the perfect counterbalance to a bad cold and a somewhat stressful half term holiday. 'Manning Coles' is a pseudonym for two people, Adelaide Manning and Cyril Coles, who co-wrote the entire series, and Cyril Coles actually was an undercover agent in Germany during WW1 and based some of the plots on his own experiences; the WW1 story is notably more realistic than any of the others.

Drink To Yesterday, Manning Coles (1940)
The first in the series, and by far the most serious and dark of all the ones I've read. The book has a framing device of the inquest into the mysterious death of an unknown person; we then go back in time to young Michael Kingston's schooldays and his precocious skill at languages with his equally brilliant teacher Mr Hambledon. At the outbreak of war, Mr Hambledon vanishes from the school and young Michael itches to join up and eventually does so under a false name. From there he is then recruited for intelligence work and deployed to Germany as the fake nephew of Hambledon, who is also in the spy business. One of the fascinating things about this book is that the narration, which is mostly from Michael's POV, uses whatever name he's currently going by as his name in the narration; how spies have to adopt specific identities and completely subsume themselves in them is one of the recurring themes of the book. Anyway, while undercover they collect information of various sorts and Michael gets recruited by the head of German intelligence in the area (a war-wounded aristocrat with 'flashing dark eyes' who likes to take young Michael out for dinner and sardonic conversation) and sent back to England, and rapidly discovers that life as a spy is terrifying and morally complicated and involves killing innocent people and destroying their lives. He and Hambledon have a wonderful mentor-friendship-slashy dynamic, there are adventures galore and the whole story is a very good read, though with a rather dark and unhappy ending.

Toast To Tomorrow (also titled Pray Silence, 1940)
I think this one has been my favourite so far. While Tommy Hambledon was Presumed Dead at the end of the previous book, given that the whole series is about him, it's not much of a spoiler to say no, he is not dead. In fact he is in Germany, suffering from amnesia. While amnesiac he concludes that he was a good German soldier during the war, he makes friends with a wide range of people which unfortunately include Hitler, and rises to become quite powerful in the growing Nazi party right up to when he gets his memory back. The authors just throw everything at the amnesia tropefic aspect of this, it's great; in general they love to lean in to all the spy tropes and situations and dramas. Hambledon then sets about trying to make contact with London and sending them intelligence without getting himself killed by the Nazis. Tons of exciting adventures of Hambledon living undercover and trying to figure out how to make the best of his unexpected situation, with unexpected allies and enemies and all sorts of spy shenanigans and a fascinating depiction of Germany just before WW2 got started.

They Tell No Tales (1941)
Back in England in 1938, Hambledon and his faithful comrade acquired in the previous book settle down to live together near Portsmouth and are given a young and somewhat feckless agent to help them investigate why naval ships keep mysteriously blowing up. This one has a large and complicated cast and is closer to a murder mystery than a spy novel, though it's very good fun as that, with all sorts of shenanigans and near-misses and a ruthless German spy ring and Hambledon trying to teach his young agent some survival skills as he sends him out to tackle the problem. The story has disguises and mysterious shootings and red herrings and all the trimmings of a classic spy/crime drama and I had a blast with this one too.

Without Lawful Authority (1943)
This introduces two new main characters, Warnford and Marden. Warnford was a military engineer working on new designs for tanks who was cashiered after his designs mysteriously found their way into the enemy's hands; Marden is the gentleman burglar Warnford caught trying to rob his safe. In the classic Golden Age style they like each other instantly and team up to set about trying to clear Warnford's name and catch the spy who really did steal the tank designs. In the process of this they stumble across an amazing number of other spies, whom they capture, tie them up and leave with a note for Hambledon to tidy up, so then Hambledon is trying to figure out which rogue agents are catching German spies for him. It's a great romp of a plot, though somewhat marred by the ending which involves a showdown in a lunatic asylum which - well, it's period-typical, but not in a good way. But all the same it was a fun light read and Warnford and Marden are great.

And I am looking forward to reading more of these, I believe Hambledon returns undercover to Germany in the next one which should be excellent.