A young woman who asked to 'die with dignity' spent four days waking up and screaming in agonising pain, while her heartbroken mother had to say her final goodbyes - seven times.
Fiona, 31, asked for medication which would put her in a deep sleep as she passed away as a result of cancer, at The Margaret Centre at Whipps Cross Hospital in east London.
However, something went horribly wrong.
Fiona's divorced mother and father Clive Strong, and her boyfriend, Alex Paxton, had to endure a week of watching her in pain before she finally died as the sedation medication did not keep her from waking.
Her devastated mother Susan Strong is campaigning for euthanasia in Britain after the ordeal which finally ended for her daughter on May 1.
Mrs Strong, 61, told The Mirror:'We must have said our goodbyes six or seven times until she finally passed away,' said Susan, who described Fiona's treatment as 'terminal sedation'.
Susan Strong's agony as dying daughter, Fiona Strong, 31, woke up several times confused and in pain
'She underwent five days of continual waking and pain. Every time she fell asleep, we thought that would be it. It would be very upsetting - then she'd wake up again.
'At one point, she woke up and was thirsty. I gave her a drink and she said. 'Mum, stop trying to keep me alive.' It was scary for her as well.
'It's not what she wanted. It was torturous.
'It was more difficult [for Fiona] because she was having to say goodbyes to everybody again and again and again.
'There was no peace of mind. Even the nurses and doctors at the hospice were in distress as there was nothing further they could do to ease her suffering.'
Fiona was a passionate scuba diver and traveller who said she had 'one last long holiday left in her'
Fiona had chosen 'palliative sedation' to minimise her suffering from what can be 'unbearable' pain during her final hours. Instead, she woke up confused and in pain.
The hospice centre in Leytonstone was legally unable to do anymore than give her the sedatives.
'If she was well enough I'd have taken her to Dignitas in Switzerland,' Mrs Strong said.
'She was screaming out all the time, even with all that pain relief. It was just awful. All she wanted to do was keep her dignity in tact and be pain-free.
'We would not allow an animal to suffer like this.'
'Fiona was so stoic and brave but how she died was so unnecessary.'
Fiona was diagnosed with aggressive childhood cancer rhabdomyosarcoma in October 2015, when a tumour was discovered in sinuses around her eye and nasal cavity.
After a biopsy the cancer was confirmed and Fiona became ill as the tumor pressed on her brain.
Fiona underwent chemotherapy and radiotherapy but spent her 29th birthday in intensive care.
However, she was dignified throughout and raised more than £10,000 for cancer charities.
Last January Fiona was given the 'all-clear' but within just four months the cancer returned.
The cancer spread to her neck and spine and Fiona struggled to breathe. Eventually, she was admitted to The Margaret Centre on April 9.
Fiona's family had raised a staggering £43,000 towards their £100,000 target for immunotherapy treatment,
But, it was too late.
'She had lost all mobility in her legs, couldn't walk, could partially move her neck... the tumour was growing so much it had grown into her neck,' her mother told The Mirror.
'Her tongue was swollen so she was finding it difficult to speak and eat.'
'She said, 'I really want to die with dignity', I don't want to be a vegetable where I can't speak. I can't move and I've got no quality of life,'' Susan said.
Fiona Strong was diagnosed with Rhabdomyosarcoma aged 28, in the late summer of 2015.
However, doctors and nurses were 'stunned' by the fact she kept waking up during end-of-life treatment.
'Fiona would say something poignant about us all, it was quite distressing.
'We'd think 'well that's it'. And then she'd wake up.
'The nurses were in tears.'
In her final hours Fiona could not speak and nurses were forced to suction blood clots from her mouth.
Her mother added: 'She then started making a noise as if she was calling me but couldn't speak. I got up and held her hand. She couldn't talk but she was aware I was there.
'The nurse said her breathing was getting shallower.'
Now, Mrs Strong is calling for a new system in which people can choose when they die.
She said: 'At the end of the day I didn't want to lose Fiona,but I didn't want her to be in pain.
Fiona Strong raised more than £10,000 for cancer charities before her death. The daughter of Susan Strong asked to 'die with dignity'
'She definitely should've been allowed to end her own life.
'Fiona's quality of life had diminished drastically by the end.
'There does have to be a degree of dignity. We can keep people alive but it's wrong to keep them alive if they are suffering things so great.
'I wouldn't want my worst enemy to go through what Fiona went through.'
Susan Strong is campaigning for compassionate euthanasia after her "stoic" daughter Fiona, 31, died in a hospice last month
Barts Health NHS Trust told Mirror Online: 'This was a very sad case and we offer our deepest condolences to Ms Strong's family.
'Ms Strong attended The Margaret Centre to relieve agitation she was experiencing as a result of her serious illness.
'Although we increased Ms Strong's sedation to relieve agitation as safely as we could she did experience some consciousness in her final days.
'Our priority is always to relieve any distress to patients throughout their illness and at the end of their life, and we will always strive to involve patients and their families in deciding the appropriate medication to meet their needs.'