Jon Wharnsby (pictured) recalls the agony of choosing between a terrified mother and daughter screaming on a tenth-floor stairway – or pushing on to a 14th-floor flat where residents also faced death

The apocalyptic scenes confronting firefighters inside Grenfell Tower are today revealed in detail for the first time by a rescuer who twice fought his way inside the burning building.

Jon Wharnsby recalls the agony of choosing between a terrified mother and daughter screaming on a tenth-floor stairway – or pushing on to a 14th-floor flat where residents also faced death.

In a split second, he and a crewmate reached the same decision. Bellowing at each other through breathing masks, they agreed: the people choking on fumes in front of them could be saved; the fate of residents higher up was less certain.

Without help, the woman and her girl would have needed a miracle to make it downstairs through the thick, choking smoke.

Minutes after carrying them to safety, Jon and crew partner Terry Lowe were back inside, again trying to reach the 14th floor.

By now, the smoke was swirling lower and thicker. They were forced to step over residents collapsed on the stairs with firefighters attending to them.

By the eighth floor, the heat had reached a new, raw intensity. When they found another mother and young girl clinging to a handrail, too frightened and confused to move, they again had to choose the living and head downstairs. Jon is haunted by the memory. ‘We ran into an apocalypse like every firefighter that night,’ he says.

‘We were tasked to reach a flat on the 14th floor. We all wanted to make a difference. But I never got to the people in that flat. Now those numbers are locked in my head.’

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When they found another mother and young girl clinging to a handrail, too frightened and confused to move, they again had to choose the living and head downstairs

Jon says he was inspired by the incredible courage and professionalism of the 270 colleagues alongside him

In an exclusive interview with The Mail on Sunday, Jon, a Fire Brigades Union station rep, played down his role, stressing he was ‘nothing special’ and ‘had a small part’.

He was not paid for this interview. The Mail On Sunday is making a donation to a Grenfell Tower victims' appeal fund at his request.

Jon says he was inspired by the incredible courage and professionalism of the 270 colleagues alongside him. ‘People need to know the reality,’ he adds. ‘They need to know what those firefighters faced inside Grenfell Tower.’

He revealed how:

One firefighter was struck a glancing blow by someone falling or jumping from a high window. He could do nothing for the victim and stayed at his post;

A 26-year-old woman, part of Jon’s crew at Shoreditch, entered Grenfell Tower with just five days’ experience as a frontline firefighter;

London Fire Commissioner Dany Cotton missed being hit by a falling chunk of burning debris as she used a police riot shield for protection.

Jon, 37, a father-of-two with 16 years’ service, started his Red Watch night shift at 8pm on Tuesday. The evening was quiet with just a couple of routine calls which he now cannot remember. At 12.54am on Wednesday, nine miles west, the first alert about the blaze came in. As the scale of the horror unfolded, fire commanders began sending an increasing number of fire engines to the scene. Eventually, 40 vehicles were there.

Jon is haunted by the memory. ‘We ran into an apocalypse like every firefighter that night,’ he says

Shoreditch – call sign Foxtrot 241 – received its shout at 2.03am.

Jon recalls: ‘The bell went, we were down the pole and away. It took no more than 90 seconds. There was five of us riding and our guvnor starts reading from the tip [teleprinter] sheet. He says, “It’s a 40-pump fire.” Someone said, “Four pumps, surely?”

‘He repeats, “Forty pumps.” He tells us it’s a high-rise tower. And then he says our brief is FSG [Fire Survival Guidance], meaning people were definitely trapped in those flats.’

Jon will never forget his first glimpse of Grenfell Tower. ‘How can you find rational words,’ he says. ‘It was like a giant had taken a flaming sword and cut a diagonal swathe top to bottom through it.

‘One side was completely black, the other flaming orange.’ The Shoreditch crew put on their masks and headed for the main entrance. Jon was with Terry Lowe, 52, who has 20 years’ experience, Paul ‘Chester’ Desmond, 38, and 26-year-old April Cachia, who was just five days into the job.

Around them blazing debris plummeted to the ground, and the firefighters were briefly forced to shelter beneath an elevated walkway. Then they ran inside, joining ten other firefighters waiting to reach the third-floor bridgehead.

‘It was organised chaos. Everyone wanted to get to the front, to go up and help. I have never seen people push themselves like that – it was incredible'

‘If your air reserve drops too low a warning whistle sounds,’ Jon says. ‘Whistles were sounding constantly as people came down. That shows how long they’d been in the tower.

‘It was organised chaos. Everyone wanted to get to the front, to go up and help. I have never seen people push themselves like that – it was incredible.

‘It was April’s first search-and-rescue. I grabbed her helmet, looked her in the eye and repeated, “Slow and steady wins the race.” ’

He adds: ‘Of course you want to sprint up the steps. But you only have so much air, so much time. We were heading for the 14th floor. We had to make sure we could get back.

‘There were no numbers on the stairwells so everyone was told in no uncertain terms, “Count your floors.” It’s not as easy as it sounds in those conditions.

Jon will never forget his first glimpse of Grenfell Tower. ‘How can you find rational words,’ he says. ‘It was like a giant had taken a flaming sword and cut a diagonal swathe top to bottom through it.

‘On the way up we’d pass flats and hear shouts of, “Casualty – crew coming out.” They were taking down survivors and had priority. We stood back.’ A rescue worker is pictured inside the shell of Grenfell Tower today

‘We had TICs [thermal imaging cameras] but above the sixth floor they were all but useless. The smoke was so thick I could barely see into the eyepiece. At that level you could feel the heat rising. That’s some feat because our protective gear is pretty good.

‘On the way up we’d pass flats and hear shouts of, “Casualty – crew coming out.” They were taking down survivors and had priority. We stood back.’

By now, about 3am, reports were emerging of people throwing children from windows and tying bedsheets together to try to climb down. Jon and Terry had reached the tenth floor when they found a mother carrying her daughter.

‘How she was walking and still screaming in that smoke I will never know,’ Jon says.

‘Terry and I were shouting at each other through our masks. We’d reached the same conclusion. If it was this bad on the tenth floor, we might not make it to the 14th. And if we did make it to the 14th, how were we ever going to get people out without masks?

‘When that ignited we were suddenly fighting a fire that was outside, that wasn’t contained, that was spreading upwards with astonishing speed and was then working its way back inside to trap people in their homes', Jon added

‘I’m going to take a couple of weeks, see if I can process it, make sure the images don’t keep returning', said Jon. A search and rescue worker is pictured inside Grenfell Tower today

‘It was a terrible dilemma. You are tasked to go to a flat where you know people need your help. But these people also needed us'

‘We had two people with us, one a child. They needed us now. We took them down to the third floor and handed them to other crews.

‘I hope they are OK. I’d like to know some time. We then had a quick check of our air and decided to try again for the 14th floor.

‘It was probably foolhardy. This time we only made it to the eighth floor before finding another mother with a little girl in her pyjamas.

‘It was a terrible dilemma. You are tasked to go to a flat where you know people need your help. But these people also needed us. We took them down and at that point were ordered to leave the building. The fire and smoke had become just too bad.’

Outside, Jon directed high-pressure hoses on to upper flats. He met a firefighter who had been running into the building when a falling resident struck the riot shield he was holding above his head.

‘When the man looked back, he could see body parts,’ Jon reveals. ‘First aiders were already with the victim – unfortunately you can’t imagine he survived.’

Crews were visited by Commissioner Cotton and thanked for their extraordinary response. ‘It was a small gesture but it felt really genuine,’ Jon says

‘Imagine that the tower is a candle but with the wick on the outside. There’s no strategy to deal with that', said Jon

With 4am approaching, the tower was effectively lost, but desperate families still maintained hope.

‘And that was what almost broke me,’ Jon says.

‘A woman came up to me, weeping uncontrollably. She shouted at me that her son was still up on the 18th floor. She was begging us to rescue him and asking when it would happen.

‘I said we’d be with him as soon as possible. I was trying to reassure her by lying. Because, by then, as soon as possible would be too late.

‘Where you had seen a torch signalling, or a blanket or flag waving to attract our attention, one by one they slowly disappeared.

‘This is where I feel for our controllers. They are speaking over the phone to people in their last moments and then suddenly the line goes dead. How hard is that?

‘They so often get forgotten but they are brilliant.’

As dawn broke, exhausted crews could be seen sitting or lying in the shadow of the smouldering tower. Each was visited in turn by Commissioner Cotton and thanked for their extraordinary response.

‘It was a small gesture but it felt really genuine,’ Jon says. ‘She was personally handing out bottled water to crews coming down. She won a lot of respect.

As dawn broke, exhausted crews could be seen sitting or lying in the shadow of the smouldering tower

‘We joked that we nearly needed another new chief officer. She had gone into the building under cover of a borrowed police riot shield.

‘Whether that would have stopped the burning debris which landed a few feet away, I’m not sure.

‘We all noted her words at the morning press conference expressing concern for her firefighters.

‘She wants to make sure everyone who needs counselling gets it. You were told you could wait if you needed more time with a counsellor. But if others on your crew want to get home, are you going to be the one holding them back?

‘I’m going to take a couple of weeks, see if I can process it, make sure the images don’t keep returning. If they do then I’ll seek help. And any firefighter with similar doubts should do the same.’

People hold candles aloft during a vigil outside Latymer Church, close to Grenfell Tower. Jon agrees with those pointing to the cladding as the key contributor to the tragedy

Turning to his rookie colleague’s brutal introduction to the profession, he says: ‘April just got on with her job. She was being looked after well, but she went in and she did it. Seems like she’ll be a good hand.’

In terms of wider lessons, he agrees with those pointing to the cladding as the key contributor to the tragedy.

‘I’m no expert but to me the exterior cladding altered everything,’ he says. ‘When that ignited we were suddenly fighting a fire that was outside, that wasn’t contained, that was spreading upwards with astonishing speed and was then working its way back inside to trap people in their homes.

‘Imagine that the tower is a candle but with the wick on the outside. There’s no strategy to deal with that. In Shoreditch, the area we cover has increased due to surrounding stations being closed. We’ve lost one fire engine ourselves.

‘This is despite our area having the highest density of high-rise towers in London. Something has to change.’