I guess it kinda depends on if you watch it thinking the main cast are good or not. The actual portrayal of communists in the show is basically that they're working class people who constantly get beat up by police or framed for crimes.

If it was fully anti-communist then they'd be presented as terrorists, or violent extremists, or Tommy would be foiling their plots for Churchill rather than framing them.

And the sister was always presented as an opportunist. Her husband was committed and she was just going along with it begrudgingly for the first season. When the family got crazy rich, her betrayal or "growing up" was literally her becoming bourgeois. She goes from living in a hovel in the factory district to living in a mansion.