I heard the story years ago from Peggy and have always assumed (in fact, in context of how I heard it, I'm pretty certain) that he was attempting an American accent and didn't quite make it. I hope to see Peggy later this year and I'll make a point of asking her.
The question of phony accents - mid-Atlantic, 'Oirish' or 'Ooo ah' etc was one that came up regularly in the Critics Group.
Nobody had problems with singing songs from outside our culture as far as I'm concerned, as long as you managed to sound like the real 'you' not a pretend 'you'.
I have around fifty-sixty songs in my repertoire taken from Scots or Irish sources, all Anglicised to fit my accent. When we started collecting I made it a practice to learn at least 1 song from each of the people we recorded (Irish Travellers, West of Ireland, Norfolk), but it was me singing the songs, not them.
Bert - contents of Critics Group London albums as promised.
Album 1 - 'A Merry Progress to London'
Street Cries, Painters Song, Roome For Company (at Bartholemew Fair), A Merry Progress to London, Maid of Tottenham, In Newry Town, Ploughboy and The Cockney, The Bold Leiutenant, London Ordinary, London Mourning in Ashes, Lass ofd Islington, Through Moorfields, Jarvis The Coachman, The Blind Beggar, There's Nothing to be Had Without Money, Georgie Barnell, Lawyer's Lament for Charing Cross.
Album 2 - Sweet Thames Flow Softly.
Street Cries, Tottie, Judges and Juries, Parson Grocer, Betsy Baker, Plank Bed Ballad, The Jail Song, William and Phyllis, Randolph Turpin and Sugar Ray Fight, Supermarket Song, Ratcliff Highway, Outward Bound, My Jolly Sailor Bold, Streets of London, Colour Bar Strike, Landlord's Nine Questions, Sweet Thames Flow Softly
Whew!!!
Both albums were originally released on Argo - there were rumours of Topic re-releasing them; don't know if it came to anything.
Jim Carroll