London (CNN) — A rare beast has been asleep in the Irish countryside for close to half a century.

When the Old Midleton Distillery in County Cork closed its doors in 1975, after 150 years in business, several casks of trial whiskey innovations disappeared with it. They rested deep within their barrels -- until now.

On Tuesday night, a gathering of whiskey enthusiasts met in London's Old Sessions House to toast the launch of Midleton Very Rare Silent Distillery Collection, Ireland's oldest ever whiskey collection.

Its first release is a 45-year-old peated single malt, created in 1974 by master distiller emeritus Max Crockett and guarded at the abandoned distillery for three generations since.

Presented in a handblown Waterford Crystal decanter and displayed in a wooden cabinet made from reclaimed whiskey vats, there are just 48 bottles in the world. The price tag for this rare wonder is $40,000.

CNN Travel was there to have a taste.

'Unicorn whiskey'

"This is a true unicorn whiskey," says Brian Nation, head distiller at Irish Distillers, which produces Midleton Very Rare . "It was part of a series of innovation trials, never to be released or repeated."

Over 45 years of maturation, the whiskey has lost 87% of its volume, making the cask's cargo all the more precious.

As master of ceremonies, he stands as 25-milliliter glasses of the amber-hued elixir are distributed around the two tables of eagerly waiting diners. Then, with a flourish, a switch is flicked so the glasses are lit from below and the whiskey gleams.

We grasp the stems and breathe deeply, absorbing a world of rich dark spices and antique oak.

"There's a lovely earthy note of freshly cut peat and I think of leather," explains Nation, guiding us on our séance with this most rare of spirits.

"And that's given a twist by some citrus notes, particularly by what I would describe as grapefruit. The contribution of the sherry wine-seasoned cask is giving you some hints of ripe honeydew melon, but particularly red berries as well."

Our noses filled, it's time to part our lips.

Courtesy Midleton Very Rare

'Instantly rich'

Tasting a fine whiskey is like skimming stones across a lake.

The first sip breaks the surface, then the ripples of flavor spread out, but there are unexplored depths still to savor.

The Midleton Very Rare whiskey is a cask-strength 51.2% alcohol.

We taste it neat first, in order to appreciate the smoothness of the distillate and full flavor contribution at its original strength.

Nation pronounces it, "Instantly rich. The initial peppery spices slowly begin to soften as the contribution of the malted barley comes to the fore.

"We're getting lovely sweetness from what I would describe as liquorice, barley sugar and even some hints of honey. But that sweetness is given a little edge by a touch of sherbert. All of this is happening on a stern foundation of toasted oak."

The finish is slow to fade, and we're still savoring the spices and malted barley as we add a drop of water to our glasses.

The act of dilution, says Nation, "mutes the alcohol a bit and allows the other flavors to come more to the fore. It's always interesting to see how the whiskey evolves."

When a complex, balanced whiskey such as this one sits in the glass and heats up to room temperature, different flavor profiles and taste profiles are revealed on each fresh sip.

"It's bringing you on a journey all through the process," says Nation.

'Liquid history'

Carol Quinn, archivist at Irish Distillers, tells CNN Travel, "A lot of people use the phrase 'liquid history,' but I think for myself, this is the first time that I've genuinely tasted liquid history. To see something that's been silenced for so long is extraordinary."

One of the most remarkable elements of this first release, says Quinn, is that it's a peated malt. "Traditionally Irish whiskey is a mixture of malted and unmalted barley," she explains. However, this one is all malt and, on top of this, "It's peated, which is extremely unusual."

This whiskey is the first of six releases, with one release annually until the year 2025, ranging in age from 45 to 50 years old, all from the Old Midleton Distillery. The last release will coincide with the Old Midleton Distillery's 200th birthday.

Courtesy Midleton Very Rare

There will be 44 bottles of this first release for sale in the US, the UK, France and Ireland, while two bottles will be sold via ballot system through The 1825 Room, the Midleton Very Rare online members' program.

For those of more modest means, however, Midleton Very Rare has some more affordable mass-produced whiskeys, ranging in price from 180 to 310 euros.

Ronan Collins, senior brand ambassador for Irish whiskey and a former bartender at London's multi-award-winning Dandelyan , was at Old Sessions House to serve up Midleton Very Rare cocktails he'd designed for the event.

"His favorite of the whiskeys, he says, is Barry Crocket Legacy, because of its "nice oily mouth feel with some white pepper spice. It's got fresh mandarin and orange notes that burst forward."

Enjoying her whiskey post-dinner at Old Sessions House, Quinn tells CNN Travel that it's her first time trying the Silent Distillery Collection and she traveled from Ireland to do it.