I'm not sure if the query on Fred or Karl Dallas was cleared up from above. They are of course, one and the same person. Fred was Fred originally and at one stage became Karl having taken the name from someone else called Karl. It was a matter of respect for the aforementioned Karl that Fred took his name. He is still referred to (by me if nobody else) as Karl "Fred" Dallas. Although it might be more appropriate if he was called "Karl" Fred Dallas. Anyway, "What's in a name?" said James Miller to his mother Betsy. :-)
So Dr Barnet Woolf it was then, with Arnold Clayton composing the music based on another tune and for a Unity Theatre Production. Available (briefly on a 78rpm single - TRC 87). Next question please!