Although Britain may boast the world’s longest continuously operating intelligence services, they were only three decades old at the onset of the Second World War. Having learned by doing, their handlers and operatives had laid the tracks for the great challenges that lay ahead. That new expertise, however, was typically not the sort depicted in action films and sensational fiction. The real nature of intelligence work was by and large not the world of swashbuckling escapades it is often portrayed to be.

It should be apparent that despite the images conjured by popular media, agent running was dominated by unrelenting paperwork. An in-house summary of MI5’s First World War operations concluded that ‘one law emerges: success in investigation depends upon mastery of detail’. Or as John Curry’s official history evokes the slogging reality of MI5’s watchers, it was difficult to find, train, and keep ‘suitable staff for this very difficult and usually very dull work’. Surveillance reports, such as those of Ottaway and Hunter on trailing Macartney, the FPA and others, illustrate the degree to which such surveillance, a core component of agent operations, is nothing short of drudgery.

As the preceding chapters show, political dividends can flow from good intelligence, itself born of good tradecraft. In revealing opponents’ intentions and operating methods, well-practised human intelligence and the high quality of what it produces can give policymakers an advantage in making decisions. Knowing what one is up against can allow better strategic and tactical calculations. At the extremes, it can change the course of the major rivers of history. Whether policymakers use intelligence wisely, or even at all, is another matter altogether.

It remains to be answered, for example, what intelligence – if any – would have convinced Chamberlain to take a different track in the run-up to the Munich Crisis. SIS at times provided sound tactical intelligence, but what little of their strategic assessments exists in the public domain situates SIS squarely in the camp of endorsing Chamberlain’s position. From some quarters, such as MI5, the message was consistent and clear: reports that did attempt to counsel policymakers on Germany’s determined expansionism went unheeded.