The firefighter who confronted one of the 21 July suicide bombers after his failed attacks feared passengers were going to be killed with a "dirty bomb".
Angus Campbell confronting Ramzi Mohammed
Angus Campbell stayed on the Tube to shout at Ramzi Mohammed after the bomber's main device failed to explode.
Mr Campbell helped a panicking woman with a baby off the train before shouting at the would-be bomber.
The BBC understands fire chiefs are recommending Mr Campbell for a bravery reward for standing up to Mohammed.
Mr Campbell, 43, was off duty and travelling on the northbound Northern Line tube train at approximately 12.30pm when Ramzi Mohammed boarded at Stockwell, carrying his bomb in his rucksack.
Turned towards mother
During the trial, the court heard how Mohammed, found guilty of conspiracy to murder, turned so that his bomb faced a mother and child before attempting to detonate the device. The entire attack was caught clearly on the carriage's two CCTV cameras.
"Ramzi Mohammed himself was screaming," Mr Campbell told the BBC. "I remember quite clearly his screaming and shouting and he was flapping at his arms and flapping at his back as though there was something alight on his back.
"There was smoke issuing from him and from his back and there was also a large amount of smoke issuing from the debris on the floor that had been caused by the attempted detonation."
Mr Campbell told the BBC that in the initial chaos he tried to flee the scene - but realised a woman and baby were trapped. He went to their aid to help her leave the carriage.
"I was underground, I was in a tunnel and I was on a moving train and there was no help coming my way. Anyway, I pulled the woman back and at this stage I think I had my first shouted conversation with Ramzi Mohammed.
Firefighter: Helped other passengers flee scene
"I asked him repeatedly what had he done, what had he done?"
On the CCTV images released in court, Mr Campbell can be seen but not heard remonstrating with the bomber, pointing at him and the remains of the device on the floor of the carriage.
Mohammed stands there, apparently in shock, shrugging his shoulders. Mr Campbell was wearing a t-shirt at the time and the word "London" is clearly visible across his back.
"I said: 'What's that? What's that?' pointing to the still smoking object that was smoking on the floor. He indicated and laughed and said: "This is bread." One thing it wasn't - it wasn't bread."
Dirty bomb fear
Ramzi was able to escape from the firefighter and from other passengers who later gave chase as he ran through Oval station, where the train had come to a halt.
"I thought it was a bomb," said Mr Campbell. "I thought it was an explosive device. But what sort of explosive device - it didn't make sense. What he was saying it didn't make sense.
"It was flour [and then] the possibility that it could have been a dirty bomb. Had it really been a dirty bomb why were we not all lying on the floor choking and dying?
"The other thing I thought was that the detonator might possibly have a delayed device on it - and that the inevitable was actually going to happen in the very near future."
Police chiefs have hailed Mr Campbell's bravery in confronting Mohammed on the Tube and have backed calls for him to be recognised for potentially risking his life.
Critically, the confrontation delayed the bomber's escape - and meant that CCTV cameras captured more detailed evidence of Ramzi Mohammed in the train - and clearer pictures of him running through the station which had already cleared of passengers.