A stood for Alexander. C stood for Catherine, his wife, although she was usually known by her middle name, May. She died in 1970 and he remarried. The Mrs McLennan who is mentioned as living in Stanley was Mabel his second wife whom he married in 1971. Alexander (Sandy) died in May 1972. I have a newspaper cutting - possibly The Courier. Mabel died a few years ago. Alexander was the son of Alexander McLennan of Clunie, near Blairgowrie. There is a family gravestone in Caputh cemetery.
There is a lot of false information out there about A & C McLennan, even in published books. Graham Martin-Bates probably has the most accurate information still available.
William Armstrong's Spittalfield to Perth service is recorded as starting in 1923. He then had services to Blairgowrie via Lethendy, via Clunie, via Essendy and the long way via Dunkeld & Butterstone. The Clunie and Essendy routes were given separate licences in 1931 but very soon were put on one licence. McLennan was engineer / driver and purchased the business on 1st April 1945.
Armstrong's garage was always at Spittalfield (and became McLennan's), NOT Caputh as suggested in some publications.
Other bus operators taken over later were Allan & Scott, Stanley and Errol (1946), Hunter, Scone (1959), Christison, Blairgowrie (1960), Smail, Blairgowrie (1960), Keiro, Kirkmichael (1963), Harper's Garage, Blairgowrie (1964), McLachlan, Bridge of Cally (1967). At least two of these were continued under their previous name for about a year. Also the Errol to Errol Station service of McIntosh, Errol was purchased around 1948.