[MarcusBrutus]

The story doesn't explain how a spy working as a waiter, purchase manager or "artist" can gain access to military secrets.

[goodcanadian]

This is a time before the internet. Even international phone calls were prohibitively expensive for most people. In this environment, international news could be days old and highly filtered. There is value to having a person physically present reading local newspapers, listening to local newscasts, talking to locals, and so on.

Moreover, this was about establishing a long term cover. He progressed through his cover career until he became an art dealer where he most definitely would have been hob nobbing with powerful people. Even if he didn't have access to "secrets" per se, he would have had access to useful information that would otherwise be hard to obtain.

[walshemj]

Possibly to help service other spies acting as a conduit back to presumably STB

[bfuller]

Extortion, blackmail, etc

[MarcusBrutus]

For a man, a brothel operator, a private detective, or a drugs purveyor would make more sense for blackmail. How would a waiter in a nondescript location gain access to information that would allow him to blackmail? It's not like the hotel was placed near a military base or was frequented by diplomats or generals. Not to mention placing tapping devices in the Queen's furniture. The story, as presented, does not compute.