John Willcox is a part-time agent with British Intelligence.
I hesitate to further identify the organization that Willcox is an unofficial and most definitely undesiring sometime operative because that matter is rather murky. The man running the show in that department does so out of his office at the British Museum which is unfortunately for Willcox but a stone's throw from his own office at the University where Willcox teaches physics. Said man is Professor Richard Maugham and the relationship between the two is not a happy one.
A blurb about the first recorded adventure tells so much about Willcox, far better than I could, when it states, "John Willcox is an alcoholic, a physicist, and a spy, in that order. Two of the three roles he inhabits comfortably. The third is thrust upon him as he's unhappily re-introduced to a despised family tradition of unearthing hidden artifacts and evading far-from-hidden intelligence services. [The year is] 1968. The world is changing again, and forty-one-year-old John Willcox has no interest whatsoever in watching it".
As we are introduced to him, he stops at a pub on his way from attending a lecture at Cambridge, the dropping by a tavern for a drink being a near-certain event these days, we learn that he "taught physics at University College, London to a handful of minds inclined, as his was, toward theory and mathematics rather than toward explosions or the Space Science fad that had recently arisen in Surrey." Theoretical work was a whole lot safer than some of the things he has been asked to do in the past, and which he will be called upon to do again. It also had the benefit of not greatly impacting his alcohol consumption.
By the way, the lecture that he had attended was about "Plasma Refractive Effect in HCN Lasers" (whew!) or as he considered it, "ongoing American attempts to mimic fictional Martian weaponry".
Willcox is able to maintain his love of imbibing and his study of physics academically because he has a baronetcy courtesy of his heritage as well as apparently considerable financial security. Neither his title nor his money - and not even his love of liquor, for that matter - seem to produce any hesitancy on the part of British Intelligence to call upon him when someone with far more understanding of scientific matters than the average operative is needed.
Willcox's dealings with the unpleasant Maugham is, as mentioned, not a happy one; its history dating far back for both of them and involving Willcox's father, also an operative but one who did so far more willingly than his son, and his mother, , about whom a number of adventures have already been written.