I have an anecdote that doesn't really answer your question, but makes me smile.
A while back, there was a rent strike at a university which led to the activists occupying a university building for a while. One of the rooms had a large double-sided whiteboard which had the day/week schedule on one side. On the other side, there was a tally chart split into "Anarchist" and "Communist" — a joking rivalry based on the fact that the majority of organisers there would describe themselves as either communist or anarchist. It made me smile because it was a tiny slice of that shared culture that you speak of (which is much harder on the larger scale). It's such a small thing, but that joking competition did a lot to reconcile the ideological tensions that can arise in diverse activism. Of course, it helped that it was set against an incredibly vibrant and welcoming atmosphere.
This isn't expressly leftist content, but I recently found this video thought provoking. It's by a UK guy who studied history at university and now works on his family's farm. He explores the peculiar situation we have where (in his view, which is in accord with my own anecdata) UK farmers and other rural workers are overwhelmingly in favour of a socialist agricultural policy, but they vote for right wing parties.