Charles Rennie Mackintosh would not have wanted his famous art school to be faithfully rebuilt, a leading architect has said.

This week The Herald has investigated two fires at the Mackintosh building in Glasgow - one, in 2014, that gutted the Mackintosh Library, and a second four years later that destroyed the entire interior of the building.

Now, looking to the future of the Mack, Glasgow architect Alan Dunlop has said the school should look to rebuild a modern art school within the skeleton of Mackintosh's original.

His sentiments are echoed by the architect David Chipperfield, responsible for the restoration of the partially ruined Neues Museum in Berlin.

Glasgow School of Art has said it intends a "faithful restoration" of the Mack and gave a completion date of 2030 but Mr Dunlop rubbished this.

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He said: "I think it's absolutely cast an iron that it won't be done by 2030, particularly after the failure of the procurement process and there are still questions over insurance.

"I remember after the fire in 2018, almost immediately it was a knee jerk reaction that they were saying it should be rebuilt, brick by brick.

"I think Muriel Gray [then chair of the board] even said that that should be rebuilt, brick by brick.

"People were making comments and saying things like, well, we have Mackintosh's original drawings so we can just follow them.

"Mackintosh designed this building more than 100 or so years ago, and meeting contemporary building regulations wasn't part of his creative agenda."

Mr Dunlop said it would be simply impossible to replicate Mackintosh's design faithfully while taking into account modern building standards such as disabled access and fire safety, particularly post the Grenfell Tower disaster.

He added: "The things that made it a brilliant building - a Category A building - was the flow from the steps right up into what was the foyer space then from there on into the upstairs exhibition space and then the main access stairs throughout the building were at either sides of the long rectangular shape.

"And these access stairs were open, completely open, and had double height spaces in them.

"These are the things that made it really quite a significant building, quite beautiful, that would be impossible to do with today's building regulations.

"So in all kinds of ways just simply replicating the building just can't be done without really significant compromises - it is a non-starter."

Mr Dunlop also pointed to a lack of clarity in what the art school means by a "faithful reinstatement" of the building and, as a result of this, a lack of price tag on what this would cost.

He added that it is vital the Mack continues as a working art school but called for a public debate about the next steps, particularly to shore up Scotland's international standing.

Mr Dunlop said he was in discussion with a senior figure who had worked at Glasgow School of Art who now fears for the international reputation of the school.

He said: "Their reputation is shot; they're living in past glories.

"He said that people in the United States, in particular, hate them because of what's happening to the school.

"When I went to Australia just about the first thing they asked me when I was getting off the plane was what's happened to the school.

"So there are stories everywhere and genuine interest about what the next part in the process actually is."

Pritzker Prize-winning architect David Chipperfield was recently asked for his views on the Mack while speaking as part of the NORR Ed lecture series.

He said he believes the only future for the building is a faithful copy but he believes the funding cannot be found.

He said: ‘[Making a copy] is not where I’d go to originally [if I was looking at the project] because you’d like to find something some other solution.

"But I've been there [to Glasgow] and I don’t think there is any other solution."

Mr Chipperfield added: "You can rebuild it as a very high-class copy. There are enough drawings and evidence and photographs. We know enough about it.

"So I don't think it’s a technical question. I think it’s financial. It requires enormous scholarship and diligence to do such thing and, I’m sorry to say, an enormous amount of money."

Mr Dunlop said the needs of students have changed dramatically with the traditional skills of life drawing and painting no longer taught.

The building would not suit modern purposes and so be a disservice to modern students.

He said: "If Mackintosh was alive - there's absolutely no way that you can describe him as anything other than an innovator in architecture - he would be the last person who would agree just to simply rebuild something that would be there.

"He would be wanting to create something new and something interesting within the bones of the original school."

"However, I think a kind of hybrid system is actually needed - a new building set within the existing structure of the Mackintosh, which somehow again reflects his legacy.

"My attitude towards what we should do next is that we should retain the existing structure and somehow sensitively and cleverly introduce a new building into the skin of that."

He added: "If Mackintosh was alive - there's absolutely no way that you can describe him as anything other than an innovator in architecture - he would be the last person who would agree just to simply rebuild something that would be there.

"He would be wanting to create something new and something interesting within the bones of the original school."