Clive ) gurgled happily, sounding much like they
were saying :

of bus route suffixes
Not since the Bassom era. Certainly, post-war, the highest was 406F,
and that only ran on Derby Day. Plenty of D suffixes, a few "E" and
that single "F".

I remember an H1 flat fare bus in Harrow in the early seventies.

Umm, that's a prefix, not a suffix.