MacColl's 'Scot's' accent was picked up at home from two Scots born parents, one from Perthshire and the other from the Lowmands - the family had Scots neighbours and during the Depression, took in a number of Scots lodgers, all of whom Ewan learned songs from
His accent was comparable to the many kids I grew up among in 1940s-50s Liverpool who came from Irish families and who ended up with a mixture of regional Irish accents from where their parents came from and the 'Scouse' they learned in the streets
If you want a prime example of this get hold of a recording of fiddle player Kevin Burke talking his very strange mixture of Cockney-Sligo (there's a recording of him doing so on the Clare County Library website (Carroll/Mackenzie collection)
As many Scots songs sung around the Urban clubs were taken from sigers from all over rural Scotland and particularly, in the case of the ballads, from Travellers who had their own exclusive way of talking, there are very few urban club singers who can caim to be singing in a 'genuine' accent

MacColl's war record really has been done to death - shame on you for digging that old 'faithful standby' up again
Jim Carroll