You can find out all about the owners of the A1 Bus Company if you buy the History Booklet of it. My copy is buried in my garage somewhere but I think there is one in Bridgeton Bus Museum, Glasgow.
Old history books of Ayrshire are available from Stark's Newsagents in Hamilton Street, Saltcoats and I'm sure they can get a copy of the A1 Bus Company Book.
It was a unique style of company co-operation with Owner Members of the Organisation being restricted to 2 buses except in rare circumstances.
They operated along the route from Ardrossan to Kilmarnock and possibly also extended to Darvel.
Every town / village on the route had a bus garage attached to an owners house. They operated by every owner setting a bus at ( I guess ) 5:30am towards Kilmarnock and the other to Ardrossan thus sharing the benefit of having no Central depot and the overhead of buses 'running light' to a start point many miles away.
From memory, Duff of Parkhouse Garage oppo Ardrossan Academy and next to it the A1 bus terminus.
Steele of Stevenston and I believe that garage still operates on Glencairn Street, stevenston ( near the Mayfield House) although Steeles had another bus and coach works just off New St, near the Rail Station.
There is one in Stevenston Road, Kilwinning just before Howie's Garage. Another in Springside and probably Crosshouse too but I cannot recall the others at the moment.
When Stagecoach eventually took them over some of the owner drivers continued with the new set-up.
I have a photo somewhere in my archives of an A1 Routemaster at the turning circle on Chapelhill Mount, the current Ardrossan Terminus. When I find it I'll post it.
I can't recall a Greyfriars pub in Stevenston but there was a Greystones Hotel at the corner of New Street and Moorpark Road West which eventually suffered a massive fire, I think now demolished.
When you were at Ardrossan Academy you were probably contemporary with Linda Duff of Parkhouse Garage ( in which Andy still has a Routemaster ).
If I rediscover my A1 history book I'll post it too because it names all co-operators and their bases.
cheers, Ian