British surveillance of Black radicals in the 1930s remained tolerant and informal

Evidence

[T]he security people, they know we are here; they come into our offices pretending to be buying books or magazines, and sometimes when we’re returning from a trip to Russia, they hold us back after crossing the Channel. But you can joke with them and say, “We’ve just been across to get some Russian gold, and we’re coming back to enrich the old country.” Instead of giving you the American cattle-prod treatment, they laugh it off. — Cedric J. Robinson, Black Marxism_ The Making of the Black…, 1235