Many of the codes are long-established, going back to London Buses Limited (LBL) (and in many cases earlier) days, and are well known among staff and enthusiasts. There is usually some sort of logic to the code allocated.
Several of the codes are long-standing, dating back to London Buses Limited (LBL) (and in many instances earlier) times, and are well recognized among staff and aficionados. Typically, there is some sort of rationale behind the code assigned.