Callie Blackwell woke once more expecting to find her son Deryn lying dead next to her.

The pair lay were sleeping just yards apart in the hospice bedroom where Deryn had been sent to spend his final few days.

He was in extraordinary pain. His frail body was battered from round after round of chemotherapy and radiotherapy, he was hooked on the painkiller morphine, was unable to eat, covered in sores, nauseous and had lost all his hair.

It was 70 days since his last bone marrow transplant and it hadn’t worked. The family knew all too well no transplant had ever grafted after more than 50 days. There was no hope left.

And, after a relentless four year battle with a one in a billion form of cancer , even Deryn was losing his previously indefatigable spirit.

“The doctors had said there was nothing more they could do,” says Callie, 37, who lives in a small Norfolk village near Bury St Edmunds.

“We celebrated Deryn’s 14th birthday in hospital and then went to the hospice to wait.”

Then, as Deryn hovered between life and death, Callie and husband Simon took a huge decision. Unbeknown to medical staff, they decided to give their son cannabis to ease his pain and anxiety.

Deryn with mum Callie, who has written about his amazing case

The couple tracked down a dealer, met him at a service station, who gave them some cannabis which they took home and cooked on the family hob in a pressure cooker following instructions they’d found online.

From it they created an oil and it was Callie who placed a tiny amount of it in Deryn’s mouth.

It worked and calmed him immediately.

But what is truly extraordinary happened next. Because the family’s hospice wait went on and on. And on. Until very slowly Deryn’s condition improved. And today he is a happy and healthy 17-year-old studying catering, with friends, a girlfriend and enjoying everything life has to offer.

The total transformation in her once so sick son still seems to bewilder Callie. But it is testament to the ferocious love and determination of one extraordinary mother.

"I’m not here to say cannabis can cure cancer or is a miracle drug", says Callie, a thoughtful and intelligent woman who was studying to become a nurse before Deryn’s last illness.

"But it did help Deryn and so I think we need to ask, ‘could it help others too?'

Deryn when he was first diagnosed at the age of 10

"I do think there needs to be more research into what cannabis can do. In some American states and across Europe it can be used.

"Obviously it is illegal so I was terrified if anyone found out what I was doing I could be stopped from seeing my dying son or lose my younger son Dylan to social services. But I had to try it. And it worked."

It was the first week of the school summer holidays and Deryn was 10 when the family’s life first changed for ever.

"Deryn had always been so incredibly healthy, he’d never had a cold, never had a day off school, was training with the local rugby team and was the strongest, fittest boy in his year. HE loved that.

"Then he started complaining his food tasted like metal and he could feel something falling inside him when he laid on his side and one morning he was sick."

He was sent for a blood test and within hours the family were called back urgently to hospital.

"We were in room 10 in the children’s assessment unit at the Norfolk and Norwich. Four doctors came in and I already knew it was going to be bad. They sat down in front of us and said there is no easy way to say this but Deryn has leukaemia .

"I burst into tears. My husband just looked totally shocked. Deryn said, ‘what’s leukaemia,’ I replied ‘cancer of the blood’. From that moment we were totally honest with Deryn about everything that was happening. Deryn has a mild autism and you have to be very blunt with him - and we felt it was his body he deserved to know.

"I tell people I wasn’t a cancer mum once but then within one second in that room I was and always will be. As soon as those words come out of the doctor’s mouth your life has changed for ever. For ever."

And Deryn didn’t just have leukaemia - he had one of the most aggressive forms with the second highest white blood count the doctors had ever found.

The next day he began brutal chemotherapy and by the second day of the September he was back at school. He’d made an extraordinary recovery - although he was still weak and prone to infection and suffered various setbacks over the next 18 months.

Deryn was ill for many years and his parents knew he was nearing death

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Then in January 2012 he started to complain about his throat hurting.

"He said it felt like a crisp stuck in his throat. I said ‘could this be a secondary cancer?"

Six months later his tonsils were removed and were found to be cancerous.

It took a further four weeks to say what kind of cancer it was because the doctors had never seen it before.

There was more chemotherapy and brutal surgery. But it seemed the cancer had come from his bone marrow and without a transplant there was a big chance it would only return again.

Again Deryn had chemotherapy to blast his own bone marrow before a donor was found in Germany. The family were crushed when the first transplant failed to work. And then a second failed too.

Deryn’s only hope was to put a small remaining amount of his own bone marrow back in. Again the first attempt failed. There was just one last bag of bone marrow left - if that didn’t work there was no hope for Deryn. He would have no immune system and be unable to fight any infection.

"By day 46 of the transplant the bone marrow still wasn’t working," says Callie. "We’d been talking to the staff for days about it and it was agreed that would be the day all his antibiotics and treatment were turned off and we went to the hospice."

His parents knew that withdrawing Deryn's antibiotics would kill him

‘We knew Deryn had only been kept alive by antibiotics by then. With no immune system as soon as the antibiotics were turned off he would be killed by any infection. I likened it to a life support machine even though he was conscious – we knew once that was switched off that was it.

“I said to the doctor how long are we talking once it’s switched off? He replied: ‘Three days. A week at most.

“We’d had so many years building up to this and although the reality was I am going to lose my son, my first born and it was horrific, just horrific, we got on with it. There was nothing we could do to stop it and no amount of screaming and shouting was going to prevent it.

"I knew the doctors had tried everything and I trusted them implicitly but everything they could offer wasn’t enough.”

At the hospice the family celebrated Christmas on December 14th knowing Deryn wouldn’t make it until December 25th.

"He was so ill by then," says Callie. "He was being sick, he hadn’t eaten food in seven months, his mouth was full of blisters, he couldn’t swallow, his body was covered in sores, he had an infected hand where he’d caught it in the side of his bed and he was quite down.

"Throughout everything he’d always said, ‘you don’t need to worry about me mum, I’m not going to die'. But now he was saying he was ready to go. He said he either wanted to be dead or be well but he was neither and he’d been like that for years.

"He’s a very spiritual person too and he said he had dreams about passing and it was beautiful and peaceful. He wasn’t scared."

In this life though there was only suffering and anxiety for Deryn - and it was that which made Callie and Simon decide to give him cannabis which they’d read online could provide comfort for people suffering as he was.

Then one day a week later after she started the treatment, Deryn’s bandage on his infected hand fell off. What lay beneath the bandage astonished the family. The hand had healed.

"I knew you can’t even produce cells without a bone marrow," says Callie. ‘It meant he was getting better. The doctors rushed in and he had more tests in his bone marrow which showed his blood count was improving. The do not resuscitate signs were shredded. Deryn wasn’t dying any more."

Over the next few weeks Callie continued to secretly administer the cannabis - and by altering the doses could see it was having a direct result on his blood count.

Within weeks the family had left the hospice and Deryn was so improved Callie stopped the cannabis treatment.

Since then he has never had any further interventions and gone from strength to strength.

In many ways it seems nothing short of a miracle.

Yet Callie is not so sure.

Callie has written a book to share her extraordinary experience

"That’s really why I’ve written the book. I had so many people contact me with very sick children saying: ‘we’re praying for a miracle like Deryn had," and I felt I had a duty to tell them the truth and I don’t believe it was a miracle.

"I am very scared of doing this because it is illegal but I feel I have to do it. And I don’t like the ‘cure’ word. But I do know Deryn is with us now.

"Through everything I. Always believed things happen for a reason and now I think maybe that reason is to tell Deryn’s story to others. And hopefully it may start a wider conversation about treatments for cancer and help others. Then, yes, it will all have been for a good reason."

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