For seven months now, I have been living under a death threat. Outwardly, my life appears fine: I have a busy family life with three children at primary school; I've just completed writing and producing a four-part drama for ITV; I seem vital, strong, full of life.
And why not? I eat healthily, I swim, I go to the gym every other day. Which makes it all the more surreal to know I have a tumour growing in my liver that will kill me unless I receive a liver transplant in the very near future.
I am only one of thousands of patients on organ transplant lists in Britain, living on our own, invisible, death row.
When I was diagnosed with a primary liver tumour in January, it wasn't the first time: four-and-half-years ago I had surgery to remove a tumour. Having had this surgery, a transplant is now the only treatment option. But more than treatment, transplant offers the possibility of a complete cure, of a body free of cancer cells. Salvation.
When I was put on the transplant waiting list in February, my prospects were good. The tumour had been picked up early. At 49, I'm relatively young and fit -- I haven't drunk alcohol for 15 years, haven't smoked in 20. Patients in my blood group, B, were being transplanted quite quickly, about every three or four months. Britain's National Health Service (NHS) was going to save my life.
Seven months later, things look very different. At the Royal Infirmary in Edinburgh, the transplant centre where I am a patient, blood group B transplants are down compared with previous years. For some reason, no one quite understands, there is now a shortage of blood group B organs in the UK.
I am heading for a crisis and so is the system. Patient numbers on the "B" list are growing and with that waiting times. This carries a lethal significance. In my case, if the tumour were to grow beyond a certain diameter, I would no longer be eligible for a transplant as the risk of cancer spreading to other organs would be considered too great.
If my tumour passes this limit before a donor becomes available, I will be taken off the list. I will be beyond help. The tumour will inexorably overwhelm my liver and kill me.
Each day without a donor is a step closer to this calamity, to "going off the list''. On the other hand, a donor means I get my life back.
It's a weird experience living with such extreme threat and promise. It's why I'm staring into the bathroom mirror at 4am, still incredulous at this patient I've become. There are times the world he inhabits -- hospitals, scans, donor organs -- feels uncertain to me, alien, more like a dreamscape.
I enter into my normal life so intensely I lose all thought of "him" and his illness. On other occasions, there is only his overwhelming threat. I'm living two parallel narratives with reality suspended as I wait for them to connect.
Waiting lists are everything. People wondered why Steve Jobs, suffering from liver cancer, chose a relatively obscure hospital in Memphis for his transplant. It has one of the shortest waiting times in America.
I keep working. I'm writing a new series for the BBC. After my first bout with cancer, I won an Emmy for my work on the final episodes of Prime Suspect. I poured myself into a dramatisation of The Passion for the BBC, identifying deeply with its themes of suffering and redemption. I dealt even more directly with my experience of pain and hope in a screenplay, Gaza, about a secular Jewish doctor in the Middle East. Helen Mirren is to play the central character next year. Will I get to see the finished film? Who knows?
Little changes at home, I take the kids to school, we celebrate birthdays and argue over whether they're old enough to walk to school on their own. They probably are but the one thing I know for certain is they're not old enough to be without their dad. The thought of them losing their father at this point in their lives feels unbearable, too cruel to contemplate, yet each day that passes it comes closer. Or not.
The phone could ring as I'm writing these words, when I'm in the shower, watching television. At any moment a lifesaving phone call could come. I can't travel farther than an hour from the hospital.
Whole families are living on the list, struggling to carry on normal life, their hopes and dreams, their children's futures, in the balance. Held hostage. The doctors know exactly how to set us free.
In my case, there is nothing speculative about the treatment, no search for a miracle drug, no future cure tantalisingly out of reach. The solution is here and now. For the doctors, the surgery involved is almost routine. All they need to act is a donor organ. Had my tumour developed 12 months earlier, I would have had a transplant within months.
Everyone's frustration is palpable. I go to hospital appointments determined to retain my dignity. Even as I keep my voice steady and calmly ask about scans and tumour size, I know my brain is paralysing with fear and my eyes are becoming huge and pleading, locking on to the unfortunate consultant at the other side of the table.
These are among the most skilled medical scientists working in the world today. We have trained them and resourced them; Edinburgh Royal Infirmary is a UK centre of excellence. Yet they are reduced to looking back at me and saying things like "stay positive" and "we just have to wait". There's nothing more they can say.
A moment of silence always arrives during these meetings. Eye contact is broken because each of us is staring at what has once more become brutally apparent; there is a deadly cancer in the room that can be cured with a few hours' work, but is that going to happen? All we can do is wait -- while the tumour grows. Scenes like this are repeated day after day all over the country. All that stands between patients and life is public awareness.
There is always a pressing need for more organ donors but a key issue today is organ take-up after death. In other countries, there is a system of presumed consent. Relatives can still withhold permission but the balance is in favour of donation. Some people fear that this system diminishes the spiritual value of giving. I understand their concern but in my view presumed consent extends the scope for charity.
In Spain, there are dedicated transplant co-ordinators in every hospital. Amid the chaos and bewilderment of sudden loss, this co-ordinator is in place to give relatives the opportunity to consider whether organ donation would offer them comfort or spiritual solace in the face of overwhelming grief. A moment to consider the values, the legacy, of the deceased.
Spain has the highest rate of organ donation in the world. In the UK, we don't know how frequently -- or with what level of sensitivity -- relatives are asked to consider donation. We do know that 45pc of British families, when asked, refuse to have an organ taken -- even when the patient has signed the organ donor register.
On the other hand, there are acts of humbling generosity. Recently a family in Manchester lost their 10-year-old son in a terrible accident. His parents, remembering that he had expressed a wish to be an organ donor, consented to donation. Facing the unthinkable pain of losing a child, they thought of others. Five lives were saved by the child's organs, five families changed for ever by a single act of extraordinary compassion.
Organ donation contains a possibility almost unique in modern life. We, the general public, can make the difference. We have the power.
It's not like the economy, the climate or Afghanistan. In the world of transplants the system works, the NHS resources are there, the technology and the skills are waiting to be deployed. Your consent is the missing element in the equation of saving lives. That's pretty extraordinary.
At his press conference this week Steve Jobs, with grace and humility, thanked the donor, an anonymous car crash victim, to whom he owes his life.
All you need do is sign up as an organ donor or consent to the donation of a loved one's organs. But we don't sign up, we're busy, we don't like thinking about mortality, nothing is quite real until it affects us. I wasn't an organ donor before all this. I thought of myself as one, as being "that type of person", but I never did anything about it. It's awful to think about losing a relative or a loved one but now is the time to think what choice you or they would want to make in the midst of grief.
On one level, you can say this is a deeply selfish article. I want to draw attention to the crisis for blood group B patients and organ donation because it affects me. It's true, but this situation is a daily reality for people all over.
Men, women, children, our lives hang on the generosity of a stranger. You are that stranger. If the world is in each one of us, you have the power to change the world.