Gullberg is the (fictional) head of the small secret Section of Swedish Security that spies on members of Swedish Security. See here.
"[Gullberg]'s model was the legendary James Jesus Angleton, who had a similar position in the C.I.A., and whom he came to know personally."
-Stieg Larsson, The Girl Who Kicked The Hornet's Nest (London, 2010), Chapter 5, p. 110.
(For Angleton, see image.)
"[Gullberg] met Angleton, and he got to drink whisky at a discrete club in London with the chief of M.I.6. He was one of the elite." (p. 119)
It was suggested in the combox here that such a small and secret group as this Swedish Section might not be noticed even by the Time Patrol although the Patrol does have people in military intelligence. However, during the Cold War, the Patrol would have to know about the activities of people like Angleton and C (Fleming's "M," le Carre's "Control"). Consequently, I think that they would also know about Gullberg meeting Angleton and drinking with C.
At this point, the fictional narratives of Poul Anderson and of Stieg Larsson almost meet.