Whom our own people had to have known about— since Hemingway (another plant) who sided with the “Republicans” of Spain (namely the Communists who roped Americans into the Lincoln Brigade) knew all about Philby and how many he got killed through English/Communist/Soviet intrigue- that far back. Orwell knew Hemingway quite well and knew all about Philby’s alcoholic pal even as Philby’s daddy was an “Arabist”. The pal being Hemingway- who covered up Commie acts just as Walter Duranty was owned by Stalin (for his perversions, thus Duranty sending in reports prepared by the NKVD). It wasn’t until Gareth Jones got the Holodomor truth to William Randolph Hearst’s vast paper empire the world learned what the Soviets were all about. And the NKVD never forgot it- and murdered Jones in Manchukuo.
Hemingway was pals with Castro-supposedly assigned him, to little effect.
Every country has spies and traitors, and always has.