It's a Seventies bottling, I think, from Midleton obviously.
This predated the 'Midleton Very Rare' blend which is now issued in annual vintages.
It was considered a premium 'liqueur' dram for on-sale excise purposes, attracting similar levels of duty as Bushmills and Scotches, which obviously were imported into the Republic.
However, it wasn't quite the top end brand that the 'Very Rare' became (following clever marketing and the introduction of vintages.) Redbreast fell into the same category for duty too.
See comparative maximum prices here (Wexford, 1973): http://22.214.171.124/1973/en/si/0200.html
Or here (Dundalk 1972):http://www.irishstatutebook.ie/1972/en/si/0229.html
Your bottle might well be a product of the Old Midleton distillery, and that has its fans alright.
If you were selling this, its comparative rarity and its provenance from Old Midleton would likely make it attractive to the Midleton vintage collectors or those with fond memories of splashing out a full 42p a dram for it back in the day!
I'm more of a Bushmills man myself, but if you PM me, I'll make you what I believe is a fair offer. It is certainly possible that some of the keener Midleton fans may want to speak to you too if you are considering selling.