Some very interesting stuff here, Nerd, thanks for all this information. Additional notes on Robert Anderson: you were wondering if any of his songs survived into the 1950's. There were certainly plenty knocking around in the early 1900's. Vaughan Williams got the tunes to seven Anderson songs from a man called Carruthers in carlisle in 1906.(I dont know if Jenny's Complaint was one of them, but I bet Bert Lloyd did!).Kidson and Gilchrist also found Anderson songs. The only information I can offer about survivals as late as 1950 is that I heard a farmer in Tunstall(near Kirkby Lonsdale) sing "Canny Cumberland" (or part thereof) in the late 60's. So there's nothing inherently unlikely about a mysterious Mr Huxtable singing a version of an Anderson song to Bert Lloyd.
    If Lloyd did write this song and pass it off as traditional, let us not be too censorious. He worshipped the tradition; and good leftie that he was, he worshipped colliers. Words like "hewed" and "seam" were like pornography to him.Many a studious collector has been reduced to "improving" songs in one way or another: the "folk" are perverse creatures, and do not always write or transmit songs in the way us enthusiasts would like them to. The temptation to remedy these defects is very powerful, and that Lloyd may have succumbed to it is can be understood.
    Totally agree with Nerd about the "below it runs the seam" bit. THis is so bad that I am almost tempted to believe in the elusive Mr Huxtable...I can't quite credit that Bert Lloyd would be so lacking in self-censorship as to try to pass that off as the genuine article.