It's first and foremost a consumer product, but whiskey is increasingly becoming the subject of investor interest - with some rare bottles selling for tens and even hundreds of thousands of euro in the past year.

That has led some to invest at the ground floor - while the liquid is still in a cask - in the hope of making a return when it is eventually mature.

Cask investments have been a feature of the scottish whisky market for some time but an increasing number of Irish distilleries are beginning to offer them too.

"They contact us and ask for a new-made cask of whiskey, we obviously have that in the distillery so we assign that cask to them," said James Brooks, manager of the whiskey cask club at West Cork Distillers. "Once that paper work is dealt with we actually store that cask in our bonded warehouse in Skibbereen,

"It has to stay in bonded warehouse for a minimum of three years before it’s classified as Irish whiskey, and at that point you are the legal and beneficial owner of that cask - you are free to do whatever you want with that cask."

Its cask-selling programme is now going into its third year - and James says it has attracted a variety of buyers, from whiskey hobbyists to those hoping to eventually make a profit on their investment.

But what’s in it for the distillery?

"It certainly has benefitted is from a cash-flow perspective - obviously this industry is very cash intensive, when you produce something you have to sit on it for three years before you can actually generate anything on it," he said. "But the other thing is that, we have approximately 550-odd people who’ve bought casks from us over the past 18 months, and we very much view those people as almost brand ambassadors."

West Cork Distillers is part of a growing global trend around whiskey as an investment - one that recently led the spirit to be added to the Knight Frank Wealth Report

"We added whiskey a couple of years ago, basically off the back of a lot of interest from our clients in Asia - and particularly China," said Andrew Shirley, editor of the Knight Frank wealth report. "They’ve been collecting fine wines in that part of the world for some time, but what we noted was that they were switching away from wine into something new - which was rare whiskey.

"Over the past 10 years a basket of collectible, single malt Scotches has risen in value by 535%."

But would-be investors are advised to proceed with caution.

"It’s never been easier to get a cask of Irish whiskey, before you do that really need to know what you want to get back from the transaction," said Peter Mulryan, founder and CEO of Blackwater Distillery in Waterford - which has never offered a cask programme, and has no plans to do so.

"There are lots of hidden charges, and lots of red tape, because you’re dealing with alcohol and it’s a highly controlled substance," he said. "You do have to proceed with caution if you want to invest for a financial return."

People should also realise that the price being secured by Irish whiskey today is not necessarily the same they will get when it comes time to sell their own.

"At the moment I think we’re at about 36 operational distilleries, all producing whiskey," said Peter. "So, in five years time, it’s not going to be as scarce as it is now. And people often quote casks or bottles of whiskey going for an awful lot of money, that’s because it’s a brand... just liquid sloshing around in a barrel is difficult to sell."

Buyers should also be particularly careful with newer distilleries that haven’t yet had any of their own whiskey come off the bottling line - as the actual quality of their end-product is still unknown.

"If you’re buying a cask for the love of whiskey and the fun and for the journey, then fantastic, just go to a distillery - most will be happy to talk to you," Peter says. "If, however, you are doing this as an investment then really, really, you need to tread incredibly carefully."