Most talking-vehicle stories give the vehicle a big personality and leave it there. RM 168 via Waterloo has a big personality and a grievance, which is considerably more useful.
His destination board says LONDON. His side panel says 168 — No pictures! No rides! — via WATERLOO. He is, in other words, a famous Londoner who would like to be left alone, and he has been left alone for so long that being heard at all comes as a shock.
The entrance requirement
Only people with a very big imagination can hear him. That single rule does a lot of work across three books. It explains why the adults never notice anything. It explains why Mark believes Beatrice without ever meeting the Bus himself. And it quietly tells every child reading that the qualification is not age, or height, or being good at school.
Sundays
The friendship settles into a routine: every Sunday, the two of them go out into a London that other people walk straight past. He is proud, easily offended and completely reliable when it matters — which is a fair description of most of the best friends anyone has.
