Looks like no one is coming up with an answer to this. I thought some of my contemporaries might have.

I am talking about the livery of the boarding/platform/staircase area.

When blue & cream was introduced, buses from each garage got a different application of the colours in this area. Donnybrook buses were totally cream.
Clontarf had blue under the stairs (where prams etc were stored).
Ringsend buses had blue up to below window level at this inside of the rear, and the panelling where the "misfare" box was.
Summerhill had blue on the rise of the stairs.
Conyngham Rd. had blue on the inside of the rear, including surrounds of the rear window.

I am almost certain of which garage was which - I am 100% certain of CT and CR - you may notice I have edited the top posting to reverse SH and RE "on mature recollection".

After some years, it was decided to standardise on the middle one, the Rinsgend livery.

Buses that moved garage generally were not repainted, so you could deduce what garage a bus came from if it was moved. The exception was that CR always painted their platforms and staircases in their blue livery when transferred from other garages - and it was always of poor quality and looked awful.