Belated reply to Terry McDonald;
MacColl was born and brought up in Salford, which makes it fairly logical that he sould write about what he knows best.
Having said which, a number of the Travellers songs were based on his interviews of Scots Travellers, and one of his best songs was, in my opinion, 'The Tenant Farmer' which was entirely Scots in subject and feeling.
Jim Carroll
PS He also did more than any singer I know to popularise the Scots ballads, putting 127 of them back into the repertoire.