I certainly don't recall his singing 16 Tons, any more than Sam Bass, at Ballads&Blues at the Princess Louise. I wonder when he would have done: it was not all that long since he had given up the theatre to concentrate on the Folk Revival; to the contempt, as he mentions in Journeyman, of such literary luminaries as Louis MacNeice and Hugh McDiarmid. He made early 78 records, on HMV I think, of Van Diemans Land, Lord Randall, Eppie Morrie, Sir Patrick Spens; & started off an embryonic B&B with Joan Littlewood at Theatre Royal Stratford; but by the time he started occasional guesting at Nancy Whiskey Club at the Louise, with Peggy as accompanist & sometimes with Bert, in the months before taking over the venue with B&B, he was very insistent that, tho it was a skiffle&folk club, he knew nothing about skiffle but was a Scots/English folksinger. Did he sing 16 Tons at Stratford E? Can't think what other stage of his career it might have come from.