The lush, fertile valley and rushing water of the Spey provided the perfect ingredients, and at their illicit whisky stills hidden from view, secretive distillers kept the water of life flowing.

As laws changed, Speyside’s reputation for whisky production emerged from the shadows; dozens of distilleries appeared, and the area became the beating heart of a booming whisky industry.

But while many of its household name distilleries eventually opened to visitors to reveal how humble barley can become liquid gold, others – perhaps in the cautious spirit of days gone by - opted to remain firmly locked.

Soon, however, whisky enthusiasts will be treated to a never-before-seen glimpse inside one of Speyside’s oldest and most productive distilleries, when it throws open its doors to the public for the first time in its 125-year history.

Speyburn distillery near Rothes in Moray, which began distilling single malt whisky in 1897, will open for behind the scenes tours and tastings as part of this spring’s Spirit of Speyside festival, a range of over 500 events devoted to celebrating the Highland region’s whisky heritage.

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For Speyburn visitors, it will be a first ever chance to set eyes on the distillery’s cutting-edge Victorian engineering, which combined emerging steam engine technology with the previously slow and laborious task of malting barley, and which helped to pave the way for a revolution in how whisky was produced.

While alongside Speyburn’s historic and listed drum malting system and original wooden washbacks, are far more modern innovations introduced as part of a recent £5 million renovation and expansion that have transformed the Victorian distillery into a modern example of sustainability and energy efficiency.

Although perhaps less famous than some other Speyside distilleries, Speyburn’s whisky played a key role in the history of Scotch: for decades, it poured almost all of its efforts into providing single malt whisky for blenders, keeping just a precious few bottles aside for local sales.

More recently, however, demand for its single malt at home and abroad has soared, while its refurbishment meant production capacity doubled from 1.8 million litres to over 4 million litres per year, making Speyburn the largest distillery in the Inver House Distillers group.

Back in 1897, however, Speyside was in the grip of its own remarkable growth spurt that would see new distilleries built across the region as demand soared.

The earlier Excise Act of 1823 had brought illicit distilling to an end and created a new, legitimate industry sparking a dash to construct new distilleries to feed demand for its product.

However, in an effort to make whisky production more profitable – and palatable – whisky blending took off, creating a second ‘boomtime’ for the sector and leading to a fresh spate of distillery construction, much of it in Speyside.

With Queen Victoria’s 60th jubilee looming, John Hopkins had resolved to create a new whisky that would mark the historic occasion.

Despite warnings it wouldn’t work, he opted to construct his new distillery alongside the Granty Burn, a tributary of the Spey and still used as its water source.

“The site was originally thought to be too steep for a distillery and without proper access,” says Lukasz Dynowiak, Speyburn’s Global brand ambassador. “But John appears to have been very strong willed, he led the project and had clear ideas about what he wanted.

“He employed Charles Doig who had a reputation as an industrial architect.”

Doig, a prolific distillery architect who would go on to design more than 50 distilleries and invented the classic distillery pagoda roof. The Doig Ventilator is a familiar feature on countless distilleries, and was used to improve malting kilns by drawing off peat smoke during the drying process.

While in the heart of Speyburn was the revolutionary drum malting system that propelled whisky production into a new, modern age. “Malting is the process of keeping barley in water and allowing it to start to germinate. Traditionally that would happen on malting floors,” adds Lukasz. “Instead of people with wooden shovels turning it by hand on malting floors, it was placed in steel drums with a steam engine and system of boilers, and it would turn very slowly.”

The system remained in operation at the distillery until the 1960s, and is still in place for visitors to view during the April tours.

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The distillery is also one of the few to still use traditional worm tub condensers. Visitors will be able to see its four original Douglas Fir wood washbacks – supplemented by newer stainless steel versions - and traditional copper stills.

During refurbishment, four of the wooden washbacks were removed and recycled to create Speyburn Fish Steps, to help fish swimming upstream in the Granty Burn.

In keeping with the distillery’s Victorian approach to innovation, a modern thermal vapour recovery system installed in 2015 has reduced emissions while co-products from production are fed to a nearby CORDe plant to generate electricity for the grid.

Euan Henderson, Distillery Manager at Speyburn, said: “We’re incredibly excited to be celebrating our 125th anniversary this year, and it is truly thrilling to welcome the public into our distillery for the very first time in our history.

“As you can imagine, after 125 years of producing single malts, Speyburn has a rich story to tell, and it’s incredibly special to share that with whisky lovers later this year.”

Speyburn is among a number of Speyside distilleries that, while others opted to throw open their doors to visitors, chose to remain firmly closed.

The doors are shut to visitors at Longmore, built on the site of an old church on the outskirts of Elgin. The distillery dates from 1893, while its whisky appears in many blended whiskies.

Its former employees include Masataka Taketsuru, who served his apprenticeship at the distillery and went on to establish the Japanese Suntory distillery.

There are no visitors allowed either at the thoroughly modern Roseisle Distillery near Burghead, opened by Diageo in 2010.

While Glenburgie near Forres, a key component in Ballantines whisky, is also closed to the public, another Speyside distillery, Coleburn, near Elgin, was mothballed and is now earmarked to be reborn as a distillery and visitor centre.

Among the events planned for the Spirit of Speyside festival is an opportunity to visit the distillery’s warehouse where whiskies from over 80 different distilleries are stored.

Lukasz added: “We always focused on the quality of the product, producing it in the right way and right operating environment, but we always knew as a company how interesting and remarkable the story is.

“Speyburn is a sleeping giant, it has significant amount of capacity in terms of production and produces these classic, amazing very full bodied and relatively sweet, very drinkable and fruity spirit.

“The 125 anniversary is a celebration for us, and we thought the best way would be to let people come inside in a proper way for the first time.”

For details of the Spirit of Speyside Whisky Festival visit www.spiritofspeyside.com . The Spirit of Speyside Whisky Festival, runs from from 26th April to 1st May.