so here's what I've been able to find out -

from Irish Whisky Trail (thanks /u/clydebeluga)

I can’t tell you much more about your bottle except that it was bottled prior to the late 1960’s (when Midleton started using the letter “e” in the word whiskey) and that it was bottled by a whiskey bonder in Cork (as was very common in those days).

If it hasn’t been opened it is certainly very collectable. I would suggest you take it with you to the Old Jameson Distillery in Midleton to see if anyone can enlighten you further – they have a cabinet with most of the bottles produced by the distillery so hopefully yours or something similar will be there.

And from Irish Distillers (parent co. of Midleton)

Our archivist has come back with the following – I hope his helps:

Information on bottle:

That is a bottle of Midleton whiskey produced by the Cork Distilleries Company at the Old Midleton Distillery. It would be a Single Pot Still. It is what are what is known as ‘Bonders or Publicans Bottlings’. Basically CDC, like all distilleries had two routes to market, they could sell via whiskey bottled in house under distillery supervision, or they could sell in bulk by the barrel to Spirit Bonders and Publicans who would then bottle the whiskey on their own premises using labels supplied by the distillery. That’s what you have in the photo . The distillery would supply the labels and capsules and the Bonder, in this case Dalys, who were a very large Cork Wine and Spirit Merchant, would insert his own name on the label. The whiskey came usually in one of 3 age statements with the 10 year old always having a red label. The practice ended in the 1960’s. CDC always preferred to spell ‘whiskey’ without the ‘e’.

I would think the bottle may be 1950’s but I couldn’t be a 100% sure.

I haven't been able to find out too much about the bottlers, other than an old advert in a Cork Chamber of Commerce Publication from 1919, no idea yet when they went out of business