PRESSURE was growing last night for answers to questions surrounding the fire which caused millions of pounds worth of damage to the Glasgow School of Art’s famous Mackintosh building at the weekend.

Chief fire officer Alasdair Hay, of the Scottish Fire and Rescue Service, yesterday refused to speculate on the cause of the fire, the second in four years to cause significant damage to the building.

Hay described the fire, which broke out late on Friday night, as one of the most significant and “heartbreaking” he had seen in his career.

Roger Billcliffe, the leading Mackintosh expert, said answers were needed, but “don’t hold your breath, we’re still waiting for answers about the 2014 fire”.

He added: “It’s well known that buildings such as Charles Rennie Mackintosh’s art school are most at risk during building work – look at Hampton Court and Windsor Castle, both extensively damaged, rebuilt and restored. So what precautions were taken at Renfrew Street? Any? None?”

Billcliffe was speaking after reports that a sprinkler system had not been fully fitted as part of the restoration following the earlier blaze.

A spokesperson for the British Automatic Fire Sprinkler Association said it was understood that automatic fire sprinklers had not been fully fitted as the building was still undergoing refurbishment from the 2014 fire.

“However, it should be realised that sprinklers can be fitted in buildings throughout construction on a temporary basis, as there is a considerable risk from fire during this period,” the association added.

The building was due to re-open next year after a £35 million renovation project had been completed following the 2014 fire and the site was in the day-to-day control of Kier Construction Scotland.

Kier’s contract was scheduled to be completed by the end of this year. The company yesterday refused to comment on whether fire sprinklers were in operation.

A spokeswoman said: “Kier has been working with the Glasgow School of Art since 2016 on the restoration of the Mackintosh building and so we share the devastation felt by the school and the wider public at this time.

“We are working closely with the Scottish Fire and Rescue Service in their investigation and as such it would be inappropriate to comment further whilst an investigation is ongoing.”

It is understood Friday night’s fire began in the building’s east wing. By the time the first fire fighters arrived on the scene only four minutes after the alarm was raised at about 23.20, it was already “well established.”

The fire also spread to nearby buildings including the popular music venue the O2 ABC, which was also badly damaged.

At the height of the blaze, a total of 120 firefighters and 20 fire engines were at the scene and nearby homes were evacuated as a precaution. Hoses brought water from the River Clyde to help fight the flames. No-one was injured.

A total of 50 firefighters, six fire engines and two high-reach appliances remained at the scene yesterday.

A statement from the Glasgow School of Art said yesterday that it had had the chance to access its adjoining buildings and the process of assessing them was now under way.

The statement added: “We have also had visible sight of the Mackintosh Building. The entire site remains under the control of Scottish Fire and Rescue Service who we have been liaising closely with since the fire broke out.’’

Muriel Gray, chair of the GSA’s board of governors, said they “remained hopeful of as positive an outcome as possible because it is clear that the love for the Mackintosh and recognition of its importance to Glasgow and the wider world is shared by absolutely everyone”.

Gray said: “We would like to express our deep gratitude to the magnificent Scottish Fire and Rescue Service, and also to extend our sympathy to our neighbours, both residents and businesses, who have also suffered, very much including the beloved O2 venue.

‘‘It is an understatement to say everyone is utterly devastated but as usual the GSA Executive Team, staff and students, have been outstanding, positive and supportive. We now have a difficult waiting game until Scottish Fire and Rescue Service , Glasgow City Council and associated agencies have completed their investigations into the condition of the building.’’

Professor Tom Inns, GSA director, said “We are heartbroken our beloved Mackintosh Building has suffered another major fire. We are eternally grateful for the professionalism and passion of the Scottish emergency services, principally the Scottish Fire and Rescue Service, who have worked tirelessly since late on Friday night to control the fire. Our entire community – staff, students, alumni, supporters and friends, will share our sadness at the events of Friday night.

“Our immediate priority is continuity for our students and staff, maintaining the educational experience for over 400 postgraduates and 1500 Open Studio students who are with us for the rest of this academic year, and planning for the 2018/19 academic year in what is clearly a challenging environment.

“However, we are strengthened by the continued messages and visible acts of support from our local community, our partners in Glasgow City Council, Scottish Funding Council, Historic Environment Scotland, the Scottish and UK Governments; and friends from across the world”.

It could be six months before the cause of the fire is known. Investigators have already begun their work.

Chief Fire Officer Alasdair Hay said that the fire service had done all it could to protect the integrity of the building.

He said: “Clearly this is an iconic building, but our fire fighters have been heroic, and done everything they can, to protect and save this building and we are working very hard with colleagues to make sure we do save the structural integrity of the building.

“This building is still in the operational phase, but structural engineers have been on site, we have been working closely with them, and will do in the coming days and we will take their advice at all stages.”

He said that in the initial stages of the fire, fire fighters had entered the building but the decision was taken quickly to withdraw and tackle it externally.

Mr Hay said “there was no one in the building by the time we arrived.”

He added: “Our fire investigation team were there on the night, they will work very closely with out colleagues, particularly within Police Scotland, to establish the full facts and the full circumstances and over the coming days and common weeks we will all be in a better position to give a full comment on that.”

In its statement the GSA pointed out that the day to day management of the Mackintosh Building site was under the control of Kier Construction Scotland and was not part of its operational estate.

Scotland’s First Minister Nicola Sturgeon visited the site over the weekend and described the damage from the latest fire as “heartbreaking”.

The leader of Glasgow City council Susan Aitken has pledged to convene a Sauchiehall Street taskforce early this week to plan the area’s future.