Are we even watching the same show ?
I remember the sister being asked by main guy on why she's not a communist anymore and the girl replied by saying "I grew up". There's also a lot of scenes where main guy collaborating with fucking Curchill, framing the Communist by bombing rail, and joining the Labour party as form of controlled opposition because "fash and bolshevism are both bad". The guy even killed the "Communist Russia" agent in the wedding episode.
Los Chikos del Maíz
I don't speak spanish but their lyrics and beats are quite good.