Your reply more than a year after my post is appreciated.
When I left Glasgow for Australia (I was ten years old) at the end 1960, the death knell on the trams had just been announced. The Trolley Buses (Whispering Death) had been slated for removal, too.
The Blue Trains had just begun their reign, although I believe they were put aside for a while due to teething problems. But they were a big improvement on the steamies. I saw a recent picture of Charing Cross Station and the difference to the station I remember from the late 1950's is absolutely amazing.
As for any modern trams breaking down and blocking the progress of those behind, I would hope that your present bus drivers don't follow the precedents set by the GCT drivers of those late 1950's who seemed to follow the rule that, under no circumstances whatsoever, do I pass the bus of a fellow driver.
Even I, from then as a ten year old kid, remember the fact that if you waited half an hour for any bus you would be rewarded by up to four in a row arriving at your stop !