I have never heard of a busker's permit in Scotland and I very much doubt if any policeman would know what one looked like.

There are some specific places in Scotland that are covered by local legislation which is probably of dubious validity if anyone wanted to spend the money challenging it. Edinburgh High Street during the Festival is the big one - they organize the place into specific "stages" during the day, with performance slots allocated. I think you have to be a paid-up Fringe act to get a slot. But 20 yards away from that area and you can do what you like.

I suspect you'd get bounced instantly if you tried busking in front of one the main stages at T in the Park, too.

Some people have been moved on under general nuisance legislation. People live in the upper High Street and the ever-increasing number of bagpipe buskers was getting beyond a joke. (This isn't some ancient time-honoured tradition, it's a way of extracting money from tourists that developed in the 1990s).