As you might gather from reading above, he was many different things and he reserved the right to be each of them despite possible contradictions, e.g. Englishman (by birth) - Scot (by heritage); traditional singer - singer/songwriter; Communist - Briton. He was incredibly prolific and so much of his musical output was of very high quality. His songs have been enthusiastically embraced by people who have heard of him. His singing is precise but seems remarkably unstudied.
I first heard of him the year I arrived in America. I first met him about 18 years later. We had a beer together at the bar of the Bull & Mouth pub in London. By that time, I had collected all of his recordings and it was quite a treat for me to have a few mintues with him. I expected him to be a towering figure physically but, to my surprise, he stood only about 5'7" or so.
He was extremely kind and gracious, very interested in the folk club I was running at The Eagle Tavern in New York and about the traditional music scene in the United States in general. I told him I was working on a collection of Irish, English and Scots folk songs and he promised to contribute a song he and Peggy had colected. Not long after, a letter and the words and music for "The Campanero" arrived in the mail.
He has been accused by some who sang with him in the Critic's Group and others as being dictatorial. Certainly, he had a masterful grasp on what he was doing. On the occasions I met him, he was close to fatherly.
Concerning his far-left political aspect, the '20s and '30s were desperate times. One can certainly understand becoming radicalized seeing people without food and shelter in the midst of great wealth. Remember that much of what was consider radical then has been incorporated in the foundation of present-day Western society: unemployment and medical insurance, government retirement benefits, 40-hour work week, etc.
I think he was quite a guy.
All the best,