Think yourself back years and years, to the very first time you heard MK speak - in an interview on TV or radio perhaps: did you identify a Scots accent? I suspect not. By that time in his life, MK was in his late twenties and had lived in several different places in the United Kingdom.
I know he was born in Glasgow but (and you guys will doubtless tell me if I'm wrong) I don't think either of his parents were Scottish. If I'm right, he would have heard little spoken Scots around the house, just friends and neighbours. And how long was he at school in Glasgow? One year or two years - something like that. I'm sure he would have had a Scots accent but probably not as deeply "ingrained" as fellow pupils, because it was not being reinforced at home. Maybe this was the time when his accent became more fluid - more Scottish at school and in the street but less Scottish at home. Just speculation, of course, but it happens.
I haven't listened to all the radio and TV broadcasts that you lot have, just a few words from the stage and the like, but I cannot recall him using any words common in Scotland but less common elsewhere - "blether", for example.
Most likely, when he moved to Newcastle and started school there, his accent did stand out. Whether it was a strong accent or not, it would have identified him as being from Scotland. [At that time, schoolkids gave one another nicknames (probably still do today) and I can recall Scottish children at English schools being given nicknames like "Jock" or, in one case, "Haggis"]. Had his parents been Scottish, I suspect more of his Scottish accent would have been retained. As it was, he began to absorb the local Newcastle accent.
And, in my view, it is that accent that he has retained. It may have softened over the years but it is still there. It is not a purely Geordie accent to my ears but it underlies aspects of his pronunciation and, occasionally, the patterns of his speech.
