A toast to Scotch whisky history: inside the Johnnie Walker archive

As archive manager she is the industry's story keeper and looks after material relating to more than 200 brands, both past and present, from more than 180 markets, in a collection so vast it is equivalent in size to 55 football pitches.

This year as the drinks company celebrates the 200th anniversary of the Johnnie Walker brand, particular focus has been on the Kilmarnock-born blends with a new exhibition in its birthplace and Edinburgh's Johnnie Walker Experience, a global visitor centre, set to open in Edinburgh at the end of this year.

Mrs McCafferty, who studied history and archiving before moving to Scotland, thinks of herself "as a bit of a detective", drawing from the artefacts stored in the environmentally controlled warehouses to help distillers and blenders develop new products or marketers map out brand strategies.

She said: "We can look at all the various source materials and build a unique proposition using historical documents or advertising and lovely visuals but we have all the really lovely stories that sit behind them."

In this way, the archive is more of a living entity than a museum of dusty relics, she says.

"It's important to me that the archive informs and inspires what we do on our brands today. If you can understand the brand's DNA, where its come from, it really helps decide what decisions to make and where we take the brand next."

Mrs McCafferty's enthusiasm for the industry is mirrored by most who work within it, she says – it's the blend of the heritage and the art of whisky making that inspires such passion.

She said: "I think it's the authenticity and the craft that still exists in creating these amazing products. And it's giving something that is really enjoyable for consumers. It's all a mixture of things about being authentic, great stories and the history.

"We like to talk about the people behind our brands. I think sometimes businesses can get so big and brands so successful that we might forget that most of them started with an individual or a family that had that bright idea to create this product and the grit and determination to build on up over the decades into the success that we have today."

And there is no one family whose ideas have been more successful than the Walkers of Kilmarnock.

After the death of John Walker's father in 1819, the teenager sold the family farm and invested in a grocers and wine and spirit shop in the East Ayrshire town.

Stocking a selection of single malts, which were known to be harsh and inconsistent, enterprising John, himself a teetotaller, began creating bespoke blends for customers who preferred a smoother dram. Soon after he started to sell a blended malt as Walker's Kilmarnock Whisky

It was his son Alexander who, after inheriting the shop in 1857, capitalised on his father's success and created the first commercial blend, Old Highland Whisky, launched in 1867. With Britain in the grips of the Industrial Revolution, the railway had arrived in Kilmarnock, allowing the brand to branch out and reach new markets, including overseas.

It was with the global expansion that came the distinctive square bottle, developed to reduce breakages in transit, and the 20 degrees slanted label, seen on every bottle made since.

In 1909, after John Walker's grandsons inherited the thriving company, the family whiskies were renamed after their label colours. Johnnie Walker Red and Johnnie Walker Black were born.

Her role in preserving the history of such an important brand comes with great pride and responsibility for Mrs McCafferty, tasked not only with preserving what has been before but also updating the archive to reflect new products, packaging and advertising from Diageo brands across the world.

She said: "It's a privilege. In 50 or 100 years time, people will be as inspired by what we're doing in 2020 as we are inspired by what people were doing before us."

The oldest item held is a bottle of Old Highland Whisky that houses not only the remnants of old John Walker's first blend but a pickled snake – a mystery that remains unsolved.

Mrs McCafferty said: "We think the bottle left Scotland without the snake and probably went somewhere in the Far East where it's not unusual for things to get pickled for whatever reason, then made its way back – it's an interesting talking point and the bottle's really important to us because its our only bottle of Old Highland Whisky."

The bottle collection, or the "liquid library", dates back to the 1880s allowing visitors to "journey back in time to see how our brands have evolved". One of Mrs McCafferty's favourite items is a stock book from John Walker and his son Alexander's grocery shop.

She said: "It tells us all the amazing things they were selling at the time they were developing their first whiskies, so there's some lovely stuff around teas, dried fruit and spices. If I could travel back in time, I'd love to experience the aromas and flavours going on in that shop as they developed their first blends, which have obviously become so successful around the world."

Some of the material housed in priceless Menstrie collection is sensitive, shared only with Diageo whisky makers, including old blending notes from the Walker family time when they were refining and defining the Johnnie Walker blend.

Unsurprisingly, Johnnie Walker is Mrs McCafferty's favoured dram, which she enjoys with a splash of ginger and a slice of lime – controversial in some circles, but certainly not to the family who founded the company.

She said: "We've got some great pictures of their blenders' room in the 1890s and they've got a soda syphon on the table. At that time it was pretty standard for people to enjoy Scotch with a mixer."