Richard Mellish wrote -
"It has been said often, but perhaps needs to be said again: there was nothing at all wrong with Bert adapting songs or even creating them from scratch, but what was very wrong was passing them off as having been made by and/or collected from someone else."

Totally agree, Richard. Bert Lloyd was an inspiring and admirable figure in the early days of the folk revival. If his deservedly respected place in the annals of folk song study has become somewhat tarnished, it is only because he has been less than straightforwardly honest about everything that he completed or 'improved'.
Robert Burns made a considerable number of alterations to the traditional songs that he included in the Scots Musical Museum and Burns and Lloyd shared the skill of being able to make their adaptations sound as though they fitted the bill.
The difference between the two is in the times that they were working in. Attitudes to authorship, copyright and intellectual property were different in the 18th and 20th centuries.