The pursuit of refugees into countries of exile is no new phenomenon. The political tumults of mid-19th century Europe sent countless people fleeing the vengeance of victorious reactionary governments. England was a popular gathering spot, having determined that it would not extradite for political offenses. England had, to some refugee leaders, an "old-established reputation ... as the safest asylum for refugees of all parties and of all countries," despite sporadic efforts to enforce statutory authority for the expulsion of aliens whose presence was embarrassing. The exiles in London found themselves hounded by the secret police of their countries, operating apparently from the sanctity of diplomatic premises. There is even some indication that the British Government cooperated in these surveillance efforts .
Michael E. Tigar,
The Foreign Sovereign Immunities Act and the Pursued Refugee: Lessons from Letelier v. Chile,
Mich. J. Int'l L.
Available at: https://repository.law.umich.edu/mjil/vol3/iss1/17