This is all TRUE.
George Formby also used to mention window cleaning. (Mr Woo's a window cleaner now, When I'm cleaning windows)
Window cleaning is a code for exposing the evil bakers etc, if you clean the windows, you make them properly transparent and you can see what is really going on.
The Song When I'm cleaning windows, is all about what people get up to behind closed doors, and is an allegory for the bankers, while Mr Wu's a window cleaner now, is a way of spreading the word and saying that even the Chinese are converts to the cause.
His assassination by the CIA concerned the song "They can't fool me" which was a thinly veiled attack on the US policy of trying to overthrow FIdel Castro while pretending not to be involved.
He died of a "Heart Attack" in March 1961, just before the Bay of Pigs Invasion.
Ironically, that all "turned out nice again" for Castro, rather than the US.