I was thinking the same thing. Someone from Govan (Rab C. Nesbitt's location, seeing as he was shown in the story) sounds nothing like someone from Milngavie or Bearsden, and if you count places with a G postcode as "Glasgow" that takes you as far out as East Kilbride or Blantyre or Rutherglen, all of which are actually in South Lanarkshire.
I'd probably be classed by most non-Scots as having a Glaswegian accent myself, despite being from about 15 miles outside Glasgow.