Francesca still has a scar on her face as a daily reminder of her ordeal. But she knows that without the actions of the nursery nurse her life would have ended right there and then.
Lisa, who now works as a community nurse in Shropshire, confronted attacker Horrett Campbell, suffering serious injuries herself. She acted as a barrier between Campbell and the children as she ushered them to safety.
The attack, at St Luke's School in Wolverhampton, shocked a nation.
Today Lisa talks about the attack – and Francesca speaks of her ongoing gratitude to the woman who saved her life.
She gave them a second chance of life and they gratefully grasped it with both hands. Francesca "Fran" Quintyne and Ahmed Malik were among the most seriously injured children saved by the bravery of Lisa Potts.
Each has since displayed his or her own brand of courage to overcome the trauma and find success.
Fran and Ahmed were, respectively, four and three years old when machete-wielding Horrett Campbell ran amok at a Midlands school 20 years ago today.
Now grown up, both hold impressive university degrees and have embarked on substantial careers – one as a hospital psychology assistant and the other as a problem-solver at a healthcare company.
They owe it all to Lisa Potts, the nursery nurse who, then aged just 21, showed extraordinary courage to protect the children from Campbell.
Despite being repeatedly slashed by the attacker she did all she could to shield her pupils and her bravery later earned her the George Medal – the nation's second highest civilian bravery award.
Now Lisa is a 41-year-old health visitor nurse working with children and their families in Shropshire and married to a policeman.
She said she doesn't allow herself to get overly emotional about the events of that day at St Luke's School in Wolverhampton, which made worldwide headlines.
She said: "Every move and moment of that day is still so clear to me but mentally I keep them out of the way in a box.
"The children are different. It touches me deeply to see them alive and well when so easily they could not have been. I still think of them as children but now they are young adults and I am so proud of them.
"The fact that they survived is almost unbelievable and, considering what they went through, the way in which they have gone on to do such wonderful things with their life is amazing."
Lisa, who has links to the Telford area and still lives in Wolverhampton, said: "I have never seen myself as a heroine but really started to appreciate the significance of what I had done after having two children of my own – especially when I took them to nursery school for the first time.
"Without my actions that day Francesca, Ahmed and Rhena would almost certainly not be alive today. I know that and also believe I am the only surviving female holder of a George Medal awarded in peacetime.
"I am proud of the way I responded to the situation but do not mention that very often because I am not a boastful person."
Lisa has been spectacularly successful in ensuring her life was not defined by those eight minutes of horror.
There is no room in her home for the medal. It hangs in a display cabinet at Wolverhampton's Civic Centre after being loaned by her to the city. She has also forgiven Horrett Campbell for the attack that left her and the children close to death.
"My faith enabled me to do that and to move on. I even feel a little sorry for him," she said.
"He turned out to be mentally ill and had not been receiving the proper treatment.
"If I had not been honestly able to forgive I would always have been consumed with bitterness and would not have gone on to do all the things that I have.
"I always questioned why he did that to them but now I fully appreciate that he was mentally ill and did it to whoever got in the way. It took me up to six years to come to terms with what had happened."
As for the children involved, who are now young adults with a full life ahead of them, they remember little or nothing of the bloodbath that stunned the nation.
But the scars, both mental and physical, have been a constant reminder of how close they came to death – and how much they owe to the nursery nurse whose extraordinary valour kept them alive.
Unlike them, Lisa has total recall of the attack that left her seriously injured. Every detail of those terrifying eight minutes of violence is indelibly etched on her memory.
She recalled: "Campbell came towards me and cut me straight across the left arm. I didn't feel any pain. I think the adrenalin was pumping round my body.
"Francesca was right next to me because I had children holding on to my skirt in fear not realising what was going on. I remember the knife coming down as if it was going to hit Francesca on the neck. I put my hand across her face and he cut her straight across the face, neck and ear."
Lisa continued: "Ahmed came running towards me with his sister. I tried to pick him up, his sister was screaming, and as I picked him up Campbell cut me across the right hand and straight across Ahmed's head.
"I grabbed Ahmed and pushed him inside the school with the other children. The man was behind me and in the doorway with me. I did not realise that I could not shut the door because my right hand was so badly injured.
"As I tried to shut the door his foot was in the doorway. I was stuck in a very small corner with dressing up stuff and toys. The door facing me led to a classroom with another 30 children inside. I tried to get into that classroom. I had got all those children in front of me and he hit me across the back, twice.
"I remember grabbing as many children as I could and, as he turned round, I started running with all those children to get out of the main building. The last blow I felt was right across the back of my head which is when he fractured my skull.
"I continued to run and looked back to see where he was. At that point he put away the machete, jumped the fence and was gone. He was not found until 48 hours later."
Fran – left with a scar from ear to mouth and two metal plates holding her jaw together – is training to be a clinical psychologist in the hope of stopping mentally damaged people from committing similar outrages in future.
Now aged 24, still living in the West Midlands, and, like Ahmed, talking publicly about the ordeal for the first time, she confessed: "It has been difficult living with the scar. It does get to me at times but I am just grateful to be alive. I owe my life to Lisa.
"I can't remember anything about the incident except him standing there. It doesn't seem real. It feels like a story. I did not forgive him for what he did to me and the others for 18 years. Then I realised that the best thing to do was to forgive him and get on with my life."
She continued: "As a teenager I ignored the whole situation and didn't want anything to do with it. I didn't speak about it at all. I tried to repress it as much as I could until it physically got to me. I went to talk to Lisa about how I felt last year because I was really struggling.
"I was in such a dark place after suppressing my feelings for so long. People tell you that they know how you feel but they don't. The only person who did was Lisa because she knows exactly what went on. She had lived it. We have a connection like a sisters' bond
"She understood what I was feeling and why I was acting in the way I did. I was able to sit with her and talk it through. That conversation lifted a huge weight off my shoulders. It was a defining moment after which I finally felt in charge of my own life.
"I was interested in psychology before I really knew what it was but the more I knew about it the more interested I became. As I got to the stage of career choices I realised I had to sort myself out and come to terms with what had happened to me. Thankfully I now have and feel free of the the cloud that hung over me for so long."
The psychology graduate, who is currently working as a hospital psychology assistant, concluded: "I want to help prevent people with mental problems doing the sort of thing that
Horrett Campbell did. I want to offer support to people who have mental health problems or emerging problems before it escalates into something horrific.
"At the same time I want to work with people who have experienced violence to assist them in coming to terms with what has happened so that they do not have mental breakdowns and depression. My own experience gives me the drive and passion to do it. My motivation is that I do not want others to go through what I have had to endure."
Ahmed was on a taster day at St Luke's School – where his sister Mariam, now 24, was already a pupil – and received a fractured skull and slash wound to his right elbow in the attack.
He graduated from Aston University last year with a masters degree in electrical and electronic engineering and now works for a healthcare company based in Hampshire. He is on the team that identifies the cause of any problem with the product and provides a solution.
The 23-year-old said: "I am not sure if I remember what happened or simply recall what other people have told me about the incident.
"I now write left handed but am not sure whether that is a direct result of the injury to my right arm. Until recently I always favoured my left hand when picking things up.
"After somebody pointed this out I made a conscious decision to use the right hand more. There is nothing physically wrong with the arm. I still get migraines but far less frequently than when I was younger. I have one every few months now. I also had nightmares when I was younger."
There are scars on his head and right elbow. He ensures his hair is long enough to obscure the former and is vague if people ask how he got the latter.
"I tend to just brush off any questions about the scar. It is not because I feel weird or ashamed about it. I am just more comfortable not talking about what happened. I am not hung up about it. I just can't be bothered going through it all. Would people believe me if I did? I can go for days or weeks without even thinking about it but it is always at the back of mind."
Ahmed went to a different nursery for a short time but soon returned to St Luke's where teachers were aware of what had happened to him. "I was not isolated but was definitely treated differently. It didn't affect me much."
He never mentioned the attack during his time at college – "it didn't come up in conversation" – and only recently discussed it with friends from Aston University.
Ahmed went on: "I don't have any feeling of ill will towards Horrett Campbell. He had mental health issues. I have seen a report in a newspaper from the time that carried a big picture of him under the headline 'Face of Evil'. That made me angry. It did not take the issue of mental illness seriously. He was not evil, he was ill and was not fully aware of what he was doing."
He added: "It feels weird thinking about my sister and the other children who were there when it happened but were not physically hurt. They did not get as much attention as we did but could have suffered just as much psychological trauma."
He concluded: "Obviously Lisa is a very special person to me. She saved my life and that is the greatest debt you can owe."
She burst into tears of pride and joy recently at an emotional reunion when he bumped into her in a supermarket while on a visit to see his family in Wolverhampton. Lisa delightedly took a "selfie" to mark the occasion.
Lisa accepts there is irony in the fact that, through the ordeal of that day, she has been exposed to new experiences and opportunities.
But she has also used it to help others.
She launched her own charity – Believe to Achieve – which helps to raise the self esteem of pupils at schools in the West Midlands in 2002, was awarded an Honorary Fellowship at Wolverhampton University six years later, completed a three-year Diploma of Higher Education in 2013 and followed that by adding a BSc in Public Health, which has now led to a new career working in the community in the Telford area.
Lisa concluded: "I cannot explain why I ran towards danger that day rather than run away. I knew there were children there I had to get out of the way. I was only 21. At that age you do not think your are invincible but you assume things will work out OK.
"Difficult things happen to all of us in life. We have to put it down as a life experience. Mine was one I hope other people do not have to experience. I could have sat around and moped but I decided to get up and go, turn it into a positive and, hopefully, inspire others."