"Walter dismissed music hall songs - it was difficult to get him to sing them"
Looking at the Musical Traditions CD mentioned above it would appear that Mike Yates had no problem getting Walter to sing this material that he dismissed.

As an amused onlooker looking at much of the above I am reminded of the story of a well known collector visiting Walter and spouting off in a "scholarly" manner about how important his material was etc etc. At the end of the guy's waffling on Walter took a long draw on his pipe looked up and slowly said "Well XXXXXXXXX, I reckon you could be right"

I wonder if this guy then went away thinking that Walter had just given his approval to what had just been said to and about him.

Just a thought.