Cap'n
Brune 'confessed' virtually on the eve of the programme being broadcast.
He succeeded in getting Sheila Stewart withdrawn from the programme - plus or minus.
Ewan,
I have outlined why the song was wanted for the programme. If it had been included as a 'genuine' travellers song it would have undermined the programme and given the knockers the excuse to end the series.
There were a number of people at the Beeb who did not approve of the Radio Ballads and thought that working people's voices should have been spoken by "proper actors". The Travelling People very nearly didn't go on because MacColl and Parker refused to remove Harry Watton's "exterminate the impossibles" statement. Parker always believed that this was the reason why there were no more Radio Ballads.   
MacColl never made any claim for his songs being traditional - others have, but not him.
Jim Carroll