Some people brag about serving scotch whisky that's 15 years old. But three bottles of Mackinlays scotch flown to Scotland by private jet Monday date back to the late 19th century.

The bottles are linked to famed explorer Ernest Shackleton's Nimrod expedition in 1907. They were found last year in a crate that had been buried beneath a basic hut Shackleton had used during the formally named British Antarctic Expedition.

The crate itself was frozen solid after more than a century beneath the Antarctic surface. But the precious bottles were found intact, and researchers could hear whisky sloshing around inside.

Antarctica's minus –30 C temperature was not enough to freeze the liquor, dating from 1896 or 1897, and experts said it was in remarkably good condition.

It is common in London's top bars to sell some aged cognacs for the equivalent of $80 a glass or more, but none of Shackleton's stash will be put on this private market, so no one will know how much consumers would have paid for such a historic dram.

The bottles, part of a cache of 11 bottles found, were judged too valuable to be returned to Scotland on a commercial flight — for reasons frequent travellers can understand — they were flown back in the private jet of Vijay Mallya, owner of Whyte & Mackay's, which bought Mackinlays some years ago.

The Mackinlays whisky will be studied and tasted in a lab for six weeks before being returned to Shackleton's hut under the floorboards of Shackleton's hut at Cape Royds on Ross Island, near Antarctica's McMurdo Sound.

The lab findings will be sent to the Antarctic Heritage Trust.