From the Straffan Butterfly Farm page:
The small mountain ringlet:
A famous butterfly collector called Mr Edwin Birchall claimed to have collected a series of these butterflies halfway up Croagh Patrick in June 1854 and one of these specimens resides in the National Museum in Dublin. There is another specimen believed to have been captured by Rev.R. McClean on the east shores of Lough Gill in 1895. Yet another collector W.F.Kane claimed to have seen specimens in the Nephin Mountains in County Mayo in 1900 although he does not seem to have captured any of them.
There are a total of 6 specimens in existence of which 3 may be genuine and 3 which are of unknown origin but could be Irish as they are labelled Kane 1903.
This is a small and elusive butterfly and difficult to find at the best of t imes in Scotland and Europe. It will only fly in bright sunshine and colonises east facing areas of grassland containing Mat Grass but the butterfly is not generally found below 2000 ft. altitude.
So why the doubt?
After 1903 Croagh Patrick was searched many times and not a single Mountain Ringlet was ever found. The Eastern shore location for the Lough Gill specimen turned out to be a most unsuitable habitat for this species and well below it’s normal altitude. Also the actual specimen label states Sligo but the eastern end of Lough Gill is in Leitrim. The Nephin Mountains are a real possibility of a suitable habitat with the inaccessable Nephin Beg being a good bet. However around 1940 the whole side of this mountain caught fire after a drought and this may have destroyed the species, if it ever existed there.
Maybe someone reading this may be encouraged to investigate and make the discovery entomologists have searched for since the start of the last century – it could be you.
Here is a gallery of small mountain ringlets. Here is a longer article on Irish small mountain ringlets.
Séamus Sweeney 
I’ve seen this butterfly in Britain at Glencoe Mountain Resort while walking in late June 2018. It was on a North facing slope at roughly 2800-3000ft although I believe they occur much lower in the Lake District in England. I didn’t find them difficult to spot but they hardly settled and the photos I took were awful, although I didn’t have much problem getting positive ID on them. I suspect that due to the nature of habit and terrain and their limited fight period, coupled to the mountain weather, they’re under-reported.
Also with access generally more restricted in Ireland, similar access laws exist on either side of the border, it’s also possible that there are areas where the public simply never go and hence never see them. It’s highly improbable that applies to Croagh Patrick or the Mournes though.
I’d say that if Mountain Ringlets have occurred in Ireland it remains perfectly possible that they are still there.
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