Hi Jim,
I'll start by saying I agree with everything you've contributed here.

However we shouldn't treat MacColl and Lloyd as the same in this context. In many ways they did similar things. I'd say probably right upto 'Travellers' Songs' no scholar this side of the Atlantic would have looked at anything produced by MacColl as necessarily having come verbatim from a source singer. However I have seen writings from American scholars even upto quite recently that take MacColl's Child Ballads for instance as unmediated, perhaps because he picked up fragments of them from his parents.

Until about 10 years ago however Lloyd's songs were treated by the majority of singers and scholars alike as unmediated and Bert should have known better. What he did was brilliant (I don't think anyone would argue with that!) but it was a deception.

The big problem with all deceivers, particularly those that have a large output, is we will never know the extent of their deception fully and therefore their work is forever tainted.