"The night bus to London is a Glaswegian rite of passage. Most people try it once, attracted by the twenty-quid ticket, the comfortable seating and the promise of arriving in London as fresh as a daisy early in the morning. Only the poor or desperate do it twice. Maureen had done it many times. She always forgot how bad the journey was until she got to the station but her experience had given her a number of tips. The upstairs deck was the most comfortable because it was far from the smell of the chemical toilet and was usually warmer, which made it possible to sleep. It tended to attract the crazies but it filled up more slowly, making it easier to get and keep a double seat to herself. The double seat was the big prize: it meant she could stretch out and leave the bus without aching everywhere."
[p. 187 of Denise Mina's 'Exile']