Update Tuesday evening, September 30: Added new information from Castle Brands (see comments).
Knappogue Castle has taken a sudden left turn and released an aged expression. They have, until now, released "vintages" which, in Knappogue's case, means stamping the bottles with the year of distillation. The most recent vintage was 1995. Bottled in 2007, the whiskey within is about 12 years old.
Now they have released a 15 year old single malt and it's not the product of a single year's distillation. Instead it's a vatting of three casks, one each from 1990, 1991 and 1992. This has yielded just 600 bottles at 43% ABV. It is not chill-filtered or coloured so there has been no interference with the natural taste of an aged malt.
Knappogue's original 1990, 1991 and 1992 vintages were made by Cooley. Subsequent production moved to Bushmills. This release is, once again, based on Cooley malt. As I've said before, the 15 year old single malt, single cask releases from Cooley have been exceptional so there is every reason to hope that this too is great whiskey.
Unfortunately (for me) Knappogue Castle 15yo will be available in select markets in the US only.