Thank you to Neil Lawrence who provided the answer. Neil wrote:
photograph above appears in new book on Edinburgh about Edwin Catford, who
worked for the old Edinburgh Corporation transport department."
The caption in the book reads:
June 1923, the
Traffic Department held the first of its annual staff
drives. The hardy souls travelled from Shrubhill to Perth
in these three solid-tyred charabancs.
journey was via Stirling, Milnathort and Glenfarg; the return
via Crief and Dunblane (remember this was a pleasure outing!).
A lunch stop
was made in Perth where OEC took this photograph at the entrance
to the station. His two sons travelled with the party, and
can just be seen at the left-hand end of the second last seat of
the furthest charabanc. His wife is in the same row."
Neil Lawrence, Fountainbridge, Edinburgh:
October 1, 2007