Twice engulfed by flames and with mystery still surrounding its future, the demise of Charles Rennie Mackintosh’s masterpiece, The Glasgow School of Art, is regarded as a national tragedy.

But for the students who once explored its nooks and crannies, dashed through its glass and timber ‘hen run’ corridor and mulled over their futures in its art nouveau library, the loss of ‘The Mack’ has been deeply personal.

Now a television documentary is set to reveal the full scale of their grief, and how devastating events that befell the beloved building left a painful scar on the cherished memories of their youth.

In it, artist, broadcaster and Glasgow School of Art graduate Calum Angus Mackay explores the deep connection he and fellow students of the past and present feel for the building, the role it has played in forging lifelong friendships and in inspiring their creative paths.

They talk movingly of their initial shock as news emerged of flames leaping from the structure in May 2014, followed by their horror as the scale of the blaze becomes clear.

Their pride at seeing the international community of Mackintosh fans, artists and students rally to raise funds for its restoration was shattered four years later by an even more devastating blaze, the memory of which brought some in the programme to tears.

While the damage to the landmark building was felt around the world, BBC Alba programme, Trusadh: Mi Fhein is Mackintosh/Art on Fire, tells how former students also grieved for the unique role it played as a ‘creative engine house’, bringing together young artists from all corners of Scotland where they shared ideas and forged friendships.

According to Calum, who studied fine art photography at ‘The Mack’ in the mid-1980s, it was more than a place of learning, and left lifelong impact on students’ lives.

“In the 1970s and 1980s, students were able to live within close reach of the art school. It was before manufactured student halls and before it was fashionable to get a flat,” adds Calum, who interviewed former and present students for the film, including his sister, who graduated in 1983, and his daughter, Sian, currently studying at Glasgow School of Art.

“A lot of students at the time were staying in hostels in Garnethill. So, in the daytime they were getting inspiration from the art school and in the evenings and weekends they were together in the neighbourhood.”

Visits from leading artists of the times confirmed Glasgow School of Art’s highly regarded status, while students from different disciplines often mixed, exchanging ideas and encouraging a flow of creativity.

“For most students, the art school building would be their starting point; their first year would be spent in the (Mackintosh) building before progressing to different departments. Usually by the second year, if you weren’t there, your friends were,” Calum says.

“Like so many of these beautiful architectural sites, you take it for granted at the time and don’t fully appreciate the beauty and the incredible detail.

“It’s once you get older you realise that there is this common bond with everyone who ever attended Glasgow School of Art. That bond and the connect to a certain degree is the actual building along with the reputation and legacy which Charles Rennie mackintosh left the people of Glasgow and the students.”

Among the school’s graduates are famous artists including Scottish painters Peter Howson, Alison Watt and Steven Campbell, writer and artist Alasdair Gray, playwright John Byrne and Kelpies’ sculptor Andy Scott. Others made their mark in other creative fields: actors Peter Capaldi and Robbie Coltrane, and musicians from top bands like Travis and Franz Ferdinand are former students.

For young painters in the early 1980s studying fine art and design like Kenneth Burns, doors which opened to reveal light-filled studios with floor to ceiling 30ft windows, and Mackintosh’s attention to detail in carvings, stonework and glass was inspirational.

“We loved the place, it was organic, it was alive, it gave you a buzz,” he says. “It gave you a lift as well because you had to be alert and know what you were doing.”

However, the risk of fire was everywhere, including from young students and tutors who smoked close to inflammable oils and materials. He recalls fire buckets filled with sand placed at strategic points along corridors in case of emergencies.

“There was obviously a great fear of this fantastic structure going on fire. It was a serious worry,” he adds.

The fear became a reality in 2014 when parts of the building, including the ‘hen run’ corridor and Mackintosh Library, was ravaged by fire. The building was set to reopen following a £35 million restoration project involving specialist builders and crafts people when the second, even more devastating fire, occurred in June 2018.

More than 120 firefighters were involved in battling the blaze which also took hold of nearby music venue, the O2 ABC.

The fire service has said its investigation into the blaze – which has already cost more than £100,000 - is expected to be completed by the end of this year. Glasgow School of Art says it will not comment until the investigation is over.

However, concerns have been expressed over the time it has taken to establish the cause, and what may happen next to the building.

The programme shows the deep emotional toll the fires had on students spanning a range of ages, including some who witnessed the flames take hold.

“They might have been there 20, 30 or 40 years ago but the common theme was how the building moulded creative people and creative students. It made me realise that what I felt for the building was common to many thousands of others,” adds Calum.

“I don’t think there is university, college or advance school in the country where students have the emotional attachment to a building that art students had to Charles Rennie Mackintosh’s building.”

Trusadh: Mi Fhein is Mackintosh/Art on Fire is on BBC Alba on Monday, August 9 at 9pm.