And with Grummet bodies, the middle one being the Austerity version. I reckon the colour scheme is two tone green with black band. This was the scheme of McConnell's Bus Lines (T L Calderwood) which was the operator of the route from 1965 to 1969. The original route number was the 101A, which began in 1940. We have George Palmer being the owner by 11/44 (maybe the original owner) but by 10/52, it had been sold to John Ormond Goller, who traded as Yarra-King buses. In 5/55, it was sold to A R McConnell who then sold it ( as above) in 1965. It was a three licence service throughout this period. Murray Coaches PL (not to be confused with Murray's Coaches of today) bought the service from McConnell's BL in 1969 and it was sold to Sita in 1975, by then the route was renumbered as the 430 (in 1971). There were route alterations about four years ago and it is now the 431.
Here is a Bruce Tilley pic of one of McConnell's BL buses taken in 1966, being the oldest in his fleet at the time and the only one in this livery. It is a Grummet bodied Reo from 1950 and it is quite possible that George Palmer was the original owner of it before the service was sold to Goller:
The rego plates of the three buses in Looselion
's post above seem to be HP 579, FT 498 and FU 452. I doubt whether that last one would get past the VicRoads censors these days. That would place them to service in late 1945, early to mid 1943 and mid to late 1943 respectively.
This thread is also of relevance:viewtopic.php?f=10&t=39108&p=443526#p443526