During World War II Stockholm became the “Casablanca of the North” and a magnet for spies. It was one of very few places in Europe where all significant intelligence services were represented. Enemies could end up living in the same building or taking the same bus. Östermalm turned into a center for diplomacy and espionage as many Americans, Russians, Brits and Germans lived and worked in this part of the city.

The British Secret Intelligence Service (commonly known as MI6) had a workplace here at Birger Jarlsgatan 12, camouflaged as a passport office.