Remember guys, the age of the whisky relates to its years in the cask BEFORE bottling, once it is in the bottle generally its flavor can only go downhill due to cork rot, evaporation through the cork, any possible damage done by prolonged exposure to extreme cold (not something normally tested on most whiskies), etc... so no matter how many years it has spent "on ice" in Antarctica it should not taste any better now than it did when bottled, and if anything maybe worse. If I remember Mackinlays was a relatively common blended whisky that just happened to be the preferred brand of Shackleton readily available at the time of the expedition.

Most of the value of these bottles is in historic terms, much like scooping a plate from the Titanic wreckage off the floor of the ocean---it is no better a plate than any other, it has just been though a historic event and lived to "tell its tale". Even for those who get to taste or scientifically evaluate it I would not be surprised if they were disappointed with its "quality" and flavor being not stellar compared to today's norms.

Although a bottle of it would be an exceptional conversation piece regardless of the taste of the whisky.

j