BSGSV

Rather more than a year or two. Repaints in the mid- to late 1980's, and I suspect that some may have gone straight from "GM Brown" to the ir livery. CIE/IR/IE "orange/tan" is probably going to be as contentious an issue as CIE Green. The latter day orange appears (to me at least) brighter than the previous orange and I would ascribe the change to Inchicore Paint Shop going over to two-pack paint in the early-2000's. The previous sprayed orange was between latter-day orange and CIE "golden brown". CIE did change suppliers over the years, and this could have led to slight variations in batches supplied too.

Given the number of industrial/private entries in "Irish Industrial and Contractors' Locomotives" (Union Publications, 1962, with amendments in a following IRRS Journal) there have been about 30 lines of 2-foot gauge in the 32 counties, and that's not counting Bord na Mona's contribution.

Is the first one the island in Cork Harbour with Camden Fort on it? Or was that even more narrow gauge?

There is a photo in an IRRS Journal showing A11 on a GAA special in Monaghan in July 1959, which I suspect is the origin for JHB's original question. The coach nearest the loco is clearly stencilled "CIE" which suggests it is of GNRI origin.