Let's get a grip!
This 'infamous' policy was confined to ONE club! And surely, at the time, if you didn't agree with that policy you just didn't sing at that particular club (there did happen to be hundreds of other clubs to choose from at the time). Where was the harm (I think that, under the circumstances which prevailed at the time, it was a GOOD policy)? What was at risk - other than egoes?

I think that this constant, tiresome harping on about that long-dead policy is a cover for those who found, and still find, MacColl's views - on folk music - not just politics - just too challenging and unconventional. And I mean unconventional in the sense that they had little too do with contemporary fashion and popular music. Now if had just picked up that Stratocaster ...