antifa?
the political left has never stopped using the term fascist as a pejorative, it's thrown around quite liberally even today
There are some hilarious misconceptions that members of those factions have about their own ideologies. Far-left is against the police brutality, but there is a 100 year history of perfect correlation between leftist regimes and policy brutality.
Far-right is against government interventions in all economic matters, but that also has never materialized anywhere else.
The bottom line is that anything that's far-something requires suppression of the society's natural tendency to return to the center.
They were certainly leftist. Many would consider them far leftist today. (Of course they weren't, but that doesn't mean the label wouldn't be applied.)
Neither was legendary for police brutality. That came later, with Thatcher's response to the Miner's Strike and the poll tax riots - among others.
It is also likely that subjects of certain British colonies would have a substantially different opinion on police violence.
By 1961, it was definitely unfair to continue using the term in its original meaning, and at this point it was certainly the Russian government pushing their agenda a lot more strongly than the general population would have on its own. But it's not like everyone was strictly opposed to it either - the horrors of the war had created in Eastern Europe such deep resentment towards Germany that it would take a lot more than 16 years to get over that. In fact, my grandpa lived until the 90s and still called every German a fascist.
[0] https://en.wikipedia.org/wiki/Fascism