I'm a bit late to this, so excuse me it this posting wanders a bit.
I think the two programmes so far have been good: they haven't named everyone or everything that mattered but how could they? They've taken a few important threads and followed them.
I was taken by the suggestion that the early collections were made with the intention of creating an English concert music as the Germans were too influential: in which case perhaps the basic inspiration came from the likes of Sibelius and Smetana, composers who raided their own folk legacies for national music. The music hall of the period could have been mentioned, too.
There did seem to be too much attention given to the blues origins of US folk, given the time allocated to Bert Lloyd, mention of his Appalachian collecting would have provided needed balance.
The knives were definitely out for Ewen McCall. Although he was given a good hearing, I think there was a little more to be said in favour of his approach. Isn't it right that the songs still existed but without their context? Yes, it was good to hear a "source singer", but surely he wasn't singing the songs in the same way at his age as would have been the case in his youth. Much of what McCall was said to be teaching was only good stage practice (as you might expect from his background). There are those today who claim that traditional songs have to be sung in particular ways: whether their way is better than McCall's I leave to others to decide, but their singlemindedness is equally inspiring/wrongheaded.
I was initially put-off by the programme following appearing to be just a repeat, but have come to feel that it is valuable to see the clips used in the main programme set in full context. Perhaps this should have been made clearer at the start.
I am an unrepentant supporter of both the "soft" face of folk as represented by the Spinners (although personally I would yell for the Blackpool Taverners), and the folk rock of Steeleye Span/Fairport Convention. Both approaches may inhabit the fringes of folkdom, but to me do show a respect for the basic material, and a popular approach to bring it to a wider audience than would ever be gained by purists. It is the people brought by popular acts, in numbers that are whittled down by time and competing interests, that became the audience folk has today.
Performers and fads come and go, the music survives.