A fire officer begged his superiors to abandon stay-put advice being given to Grenfell Tower residents within minutes of arriving at the burning block, an inquiry has heard.

Norman Harrison, a watch manager from Wembley with 25 years’ experience, was called to the scene at 1.15am on June 14 last year, quickly realising something was badly wrong.

London Fire Brigade was first alerted to the blaze at 12.54am and, in line with the fire policy for high-rise buildings, told residents to remain in their flats.

However, the speed and ferocity of the fire’s spread meant many occupants became trapped on upper floors and were left beyond the reach of rescue teams.

The stay-put advice was finally ditched at 2.47am, a delay that has been heavily criticised.

On Wednesday, it emerged at the inquiry into the disaster that Mr Harrison tried to get the stay-put strategy stopped much earlier.

He told a hearing at Holborn Bars he concluded the strategy was redundant by around 1.50am, adding: “I was truly shocked at such a severe fire over so many floors.

“Immediately I knew that stay-put policy should no longer apply in this building, because the stay-put policy is predicated upon the assumption that someone can stay in their flat, safe, from the one compartment that is alight somewhere in the building and they’re not going to be affected by the fire, either flames, heat or smoke.

“I could see that just didn’t apply here any more.”

His written statement described how the intensity of the fire on the external face of Grenfell Tower reminded him “of the surface of the sun”.

It was “bright yellow” and he had “never seen a fire like it”, it continued.

He was reminded of a recent cladding fire on a tower in Dubai and initially held out hope that the flames would remain on the facade of the building only.

Getting closer to the building it became clear the blaze had broken back into flats from the fourth floor “all the way to the top”.

“I was extremely concerned for the members of the public who were trapped inside the building,” his statement said.

“I was also concerned for my colleagues who were going to be committed into the building.”

Mr Harrison said he knew from previous experience that each flat would be designed to withstand flames for 60 minutes – but he estimated it would take six hours to reach the top floor.

“I knew that our telephone operators at Merton HQ would be telling people to stay put in their flat and that the fire brigade would come and rescue them.

“In reality I didn’t think that there would be an opportunity to rescue people on the upper floors and I strongly felt that the advice needed to be changed from the stay-put policy to almost a simultaneous decision to evacuate.”

He then rushed over to the incident command vehicle from where the operation was being directed, according to the statement.

He encountered a cluster of senior managers, including a group manager – believed to be Richard Welch – with two station managers and two watch managers.

“I announced to all of them that I believed the advice our operators were giving out to the people trapped in the building needed to be changed,” he wrote.

“I suggested that someone tell our control operators to change that advice as soon as possible. I recall that some discussion took place.

“It was mentioned that there was only one escape route – there would have been lots of firefighting hose within the very narrow stairwell.

“I then asked if it was possible to use our emergency air supply equipment. We call it a second set bag to be given to members of the public to assist them in breathing whilst being evacuated.

“I never got answered.”

Mr Harrison was sent back to his command unit vehicle, where he spent the night passing information from 999 calls with trapped residents to rescue teams in the tower.

His statement said there was only a brief timeframe when an evacuation was safe, when the fire was still only on the external face.

“I think we had a small window of opportunity to bring people down to safety, or basically as safe as it was going to be for the duration of the incident,” he said.

His statement concluded: “It was an impossible task from the off. I think it was a lose-lose situation no matter what decisions were made. People were going to die that morning. It was just a matter of how many.”

It added: “I wouldn’t say that I am any happier at work as there are still a lot of organisational failures. To tell the truth they have always been there from day one all throughout my career. I find it now harder to accept the shortcomings of the fire brigade.”