Whilst true numerically, they were introduced concurrently, not consecutively. I remember route 213 going omo in the early 1970s; those for Sutton Garage were MCW and those for Norbiton were PRV.
I regularly used the afc on my school commute - no one else did, so you could jump the queue! The machines dispensed a ticket which you needed to take before the turnstyle operated. ....unless the previous passenger had not gone past the 'magic eye' correctly, in which case you had to wave your hand to break the beam, and the turnstyle would operate again. The driver would have to leave his cab to do this, so the turnstyle was often left non-working.
The fare stage on the afc also had to be changed at each fare stage. To do this, there was a knob mounted on the right hand side of the dashboard. When the fare stages were ascending, the afc's fare stage mechanism incremented by 1; when descending, the mechanism had to 'go round the clock', so it incremented to 50, then restarted at 1, 2, 3, etc, until it reached the fare stage one less than the previous setting.