This is a reprint of the 1981 volume by this legendary author on matters of espionage. Given the steady release of more documents from the National Archives since then, and the evidence of further defectors, I am slightly surprised the opportunity was not taken to update the original volume. Nonetheless, West – a prolific author – can be relied upon to write an authoritative and readable tome. At times the prose is a little too dense, and some readers may lack the author’s enthusiasm for the minutiae of counter-espionage work.

MI5’s early years were dominated by its founder, Vernon Kell,  and West gives due credit to Kell for establishing high standards from the outset, and achieving much with little. Indeed the reader is left pondering what might have been had the UK Government properly resourced MI5 in the years leading to WW2.  The scarce resources led to some eccentricities in operation:  one of Kell’s deputies, Max Knight, ran some operations from a flat in Dolphin Square, which he had purchased in his wife’s name. There is the terrific tale of how Kell’s men set up a raid on the Soviet Trade Delegation in the City of London (Soviet Russia’s centre for espionage against the UK in 1927).

West is good at chronicling the delicate and constantly shifting relationship between MI5 and the Government of the day. Of course MI5 had to look at dangers from the far Right as well as from the Communists, and West sets out the membership of the various pro-German and pro-Fascist organisations in the UK in the Thirties. The reader is left in no doubt as to how deeply entrenched in the British establishment were Nazi sympathisers.

Once war was declared espionage and counter-espionage operations were obviously ramped up quickly; and this book leads the reader through the political struggles for control. From time to time, British eccentricities add colour to the proceedings. Not the least of which is the tale of Lord Tredegar, who indiscreetly related to a lady friend his part in the operations of the Falconry (Interceptor) Unit – falcons being used to attack the swarms of dastardly German carrier pigeons expected to transit the Channel. Tredegar was briefly imprisoned in the Tower, but after his release he was so upset he recruited the service of a renowned occultist to cast a spell on his arresting officer – who promptly became seriously ill!

MI5 became very adept at rolling up German parachutists soon after their landing, and the part played by suspicious locals is made clear. West goes into the Double Cross system in some depth, and no doubt this was the inspiration for Ben McIntyre’s successful books on the subject. Another astonishing tale in this book concerns one Dufour, a French agent of SIS, who on his return to the UK was arrested by de Gaulle’s BCRA and tortured. Escaping from their clutches in London, he issued writs in the High Court against de Gaulle and his henchmen.

The final saga in this book concerns  MI5’s fight against Irish terrorism in the UK. These days, in the light of subsequent events, it is rather overlooked that in WW2 Irish Nationalists unleashed violence and terrorism on a wide scale in the UK.  Combating this required a delicate political dance given that the Irish Government was concerned to maintain its neutrality in the conflict. West gives a good account of how MI5 navigated these muddy waters.

Overall this is an excellent book, with two provisos: it is splattered with typos, in typical Pen & Sword style. Secondly, as I said earlier, it is a slight shame it was not updated.