According to a long-awaited analysis, the fire that blasted through Glasgow School of Art’s Mackintosh building in 2018 was so intense and all-consuming that the cause will never be identified unequivocally.

The art school expressed “frustration” that the exact cause of the fire, which destroyed the iconic Grade A-listed building as it neared the end of a £35 million restoration project after a previous blaze in May 2014, had not been identified in the Scottish Fire and Rescue Service (SFRS) report, which was released on Tuesday.

According to the report, the cause of the fire has been recorded as “undetermined” after the service’s most complex and resource-intensive investigation ever, which included more than 172 weeks of excavation and examination of hundreds of tonnes of debris, as well as careful analysis of witness testimonies, CCTV, and photographic footage. However, it said that arson and electrical failure could not be “fully discounted.”

Paul Sweeney, a Scottish Labour MSP for Glasgow and a board member of the Glasgow City Heritage Trust, said he was “appalled” by the length of time it took for progress on the investigation and restoration plans, adding that the report was “barely worth the wait” and “tells us nothing we couldn’t deduce from a cursory glance at aerial photographs.”

The building was so heavily damaged by the fire, according to the report, that significant engineering work had to be done first to stabilize and make safe the surviving structure before investigators could enter the site. They noticed that most of the physical evidence, such as the Fire Warning System (FWS) control panel and the CCTV hard disk, had been severely damaged and could no longer offer information.

The first flame started when combustible vapors from a foam canister used in a student project ignited, according to an inquiry released in November of that year.

A Holyrood investigation heard criticism of “systemic failures” on the side of the art school’s administration in September 2018, three months after the second fire.

Penny Macbeth, director of the Glasgow School of Art, and Kristen Bennie, interim chair of the GSA board of governors, stated they “share the frustration that many will feel that the exact cause of the fire has not been identified,” but praised the SFRS for its “careful” investigation.

They went on to say that the assessment was an essential step forward in their Mackintosh Project, which was announced in October and would see the “faithful reinstatement” of the Mack building, albeit it won’t be ready for at least six years.

Sweeney encouraged the GSA to act as soon as possible: “Three years later, it’s still unclear when contracts will be awarded, whether it will be financed, whether the insurance will pay out, and whether we will appoint people to get this back on track.”

“This is the single biggest disaster to strike Scotland’s built heritage in a century, and the authorities, from the School of Art itself to the Scottish government, have been nothing short of disgraceful in their lack of speed and grip.”

Thanks to at The Guardian whose reporting provided the original basis for this story.