The foster parents of the Parsons Green bomber have told ITV News how they never suspected the "bright" and "lovely lad" they "loved like a son" would build a bomb in their kitchen while they were on holiday.
Penny and Ron Jones said they knew the teenage asylum seeker Ahmed Hassan as a model student destined for university, who mowed the lawn and gladly helped with shopping at the family's Surrey home he had shared for two years.
The first time they learned the Iraqi orphan was in trouble came the day after last September's Tube attack when Mrs Jones answered the phone to be told by police they had their home surrounded.
They had reported Hassan as a missing person earlier in the day after learning from a friend he had failed to attend college the day before.
Officers had told the worried couple to stay at home while they looked for him.
"We were sitting here saying they better hurry up and come because I haven't done any shopping, we've got nothing in for tea tonight," Mrs Jones told ITV News.
"We were watching something on the television and the phone went and I said 'oh hello!', and this voice said: 'This is the police, you are surrounded by armed police, put everything down and get out now!'
"And I looked up and there was two eyes at the window and a gun and I was frightened out of my life."
The couple, who have fostered 269 kids over 47 years, were forced out of their home in Sunbury-on-Thames as it was turned over by detectives.
They later only learned on TV what had really happened to their kitchen knives they thought had been mislaid.
Mrs Jones, 71, remembered: "I said to Ron that we were missing some knives, and he said, 'well you know what the boys are like, sometimes they empty their plate off into the bin and their knife has gone into the bin and down the rubbish shoot - end of story'.
"But then when I saw the pictures of the knives, on the television, I said look they haven't gone down the rubbish shoot - they are on the telly."
Hassan had used the cutlery as shrapnel in his device, along with a screwdriver set that Mrs Jones said was a "birthday present for Ron from me" and a "pot of nails and screws".
But the biggest shock was the revelation the studious teen living with them since April 2016 was a fantasist plotting mass murder in the busy morning rush hour.
"That frightened us the most," Mrs Jones said. "To think that all of my neighbours were put at immense risk, I find that really hard.
"Not only us, but I've got grandchildren that come in and out. When the boys are here we put the grandchildren in our room and we sleep down here - we've put our grandchildren at risk as well."
Mr Jones, 89, said the revelation about Hassan "came as a sudden shock" and "really upset me," and added: "I'll be honest with you, I still can’t think he's done such a thing."
The couple said they feel betrayed and dread to think what could have happened had Hassan succeeded in his bid to blow up the District Line train in west London.
"I don't think we could have lived with other peoples' lives probably lost through him," Mr Jones said. "I don't think I could have stood that."
Hassan, 18, was found guilty of attempted murder after an Old Bailey trial last week. The September 15 attack created a fireball that left 51 people injured on the packed carriage.
Hassan told the London court he made the bomb as he was "very bored, very depressed, very confused" and hoped the blast would draw attention to himself.
But the Joneses don't believe they could have done any more for a teen whose most worrying behaviour was graffitiing a door out of boredom.
"He wrote all in black felt-tip pen from top to bottom, right across the door, 'I'm bored, I'm bored, I'm bored.'" Mrs Jones recalled. "You'd ask him why and he couldn't tell you."
Mr Jones said though Hassan never spoke about his parents who died in Iraq, he and his wife made it clear as foster parents they were there to support him.
He said: "Some mornings he’d get up, he'd come through the front room door, and he’d walk with his head down a bit, and I'd look at him and say 'you alright Ahmed?' and he'd say 'yeah' and I'd say 'you sure?'.
"He said 'yeah I'm fine', and I'd say to him: 'look if there’s anything worrying you, what we're here for, talk, ask us, tell us, if you've got anything like that', and he'd say 'no I'm fine'."
Mrs Jones admitted to ITV News there was a "small part of me that cares" for the attacker, pointing to a photograph of him as "my Ahmed".
"I know he has mental health issues and that is the thing that worries me, the mental health," she said.
"There is only a very, very small part (that cares). I am cross with him for what he’s done, and that he's done this in my house makes me feel very, very betrayed, I can't help that.
"Because he's such a bright and intelligent child, he'd got a good future ahead of him. I find this hard."
Hassan's trial heard he had wanted to be the next David Attenborough.
"His photography was stunning, absolutely stunning," Mrs Jones said. "(He was) very bright and he learnt very, very quickly."
She added: "I loved him like a son. I do with all the kids, they come into my house, they are my babies, my boys, and I treat them like my boys as much as I can."
"They need to know someone cares, and that's all I've ever wanted to do, to show that I cared and that he meant something to us."
The couple fear their experience could harden hearts and close doors for others to be fostered.
They said they would take greater precautions in fostering again, having been unaware Hassan had been involved in the government’s Prevent deradicalisation programme for more than a year.
Recalling Hassan's attack, Mrs Jones said: "I'm just so glad he did it wrong. I feel really, really sorry for the people who were injured. The lady who had a burnt face, burnt legs, I really feel sorry.
"I just wish that I could have done something to help them but I can't.
"We've asked ourselves time and time again 'what did we miss?'"