From St Andrew’s Bus Station, Edinburgh, I catch the 900 bus to Glasgow. The day is overcast but warm and the bus is busy with students and pensioners taking advantage of the cheap ride to the city. Long before we reach the M8, I notice a man sitting adjacent – probably in his 30s, nondescript scruffy, looking slightly troubled, but bearing no clue to his status. Reaching into his rucksack he pulls out a packet of custard creams. I…