Dr Robert Smithson meets me in his office in the newly rebuild St Thomas' Hospital just across the Thames from the Houses of Parliament. He is approaching 48 years of age, yet looks almost 60.

Your hospital was one of the first to take in bite victims , what was your initial reaction when you realised what was going on ?

We had already heard rumours floating around from staff at other hospitals. We thought it was a prank at first, but then the casualties started rolling through our doors and into our accident and emergency department. There was a lot of confusion in those first days, nobody had a clue what was going on. Some people even thought it was some sort of new drug, or maybe a cannibal cult. We immediately clicked on that something was very wrong when patients with even just minor bites were going into toxic shock and dying in front of us, then suddenly reviving and attacking our staff, or even other patients. We resorted to restraining patients to their beds and keeping them separated from our non aggressive patients in a separate quarantine ward. We communicated with other hospitals and they were all doing the same.

We were in constant contact with the Health Protection Agency and other London hospitals, trying to comprehend how seemingly dead people were getting back up and attacking others. As the days wore on we were forced to ban family from visiting their sick relatives for obvious safety reasons. More security guards were employed and eventually we requested a round the clock police presence to keep order in the hospital as the cases mounted. There were some days that i was working up to 16 hours, and sleeping for a few hours in the canteen or the staff room then going back to work. We were increasingly understaffed as people ran home to be with their families as the capital descended further and further into chaos.

Eventually we reached the stage where the army was called in as entire neighbourhoods were overrun with the walking dead. The government released barricaded behind heavy gates in Downing Street surrounded by machineguns and tanks, whilst we worked on the front lines of the outbreak trying to save as many lives as possible.

I was looking out the window one morning as the sun came up and for the first time i realised how truly devastating the situation was outside. I saw pillars of smoke snaking into the air as helicopters buzzed around like flies. There were sirens and screams and gunshots, and even the occasion explosion from the streets just a few miles away.

My attention was finally attracted to my phone where i had just received an email, it said the following :

To : Senior Staff, St Thomas Hospital

From : The Office of the Health Secretary of the United Kingdom

The situation has deteriorated to such a degree that central government is under the impression that the security services will not be able to maintain order in London for any longer than 32 hours, perhaps less. North London is almost entirely a red zone, and the PM has taken the decision to evacuate South London in an effort to save as many lives as possible. First and foremost the elderly and vulnerable, in this case hospital patients (those not infected with Z-066A) will be first to be evacuated. All hospitals in South London still operating (both NHS and private) will be evacuated via military and Red Cross vehicles in the coming hours and transported to facilities in other parts of the country for treatment.

Department of Health is aware that some patients are too frail or ill to be evacuated without suffering serious injury or even death, which is why by the order of the Prime Minister, all Head's of Hospitals have been granted the authority to authorize their staff for euthanasia by lethal injection. It is best to inform the patients they are being given a sedative. If Next of Kin is contactable tell them they passed away from complications. Whilst this may seem cruel please understand it is far less cruel than abandoning them to the infected.

A military officer will contact you directly in the coming hours and explain in detail the evacuation process. I strongly advise you cooperate with the military, and advise your staff to do the same.

Thank you

HM GOVERNMENT

Now that's not the kind of email one is used to getting is it ? But the infection was just a few streets away. The police had withdrawn further back and only a handful of army units were left and they were buying us time to evacuate the building. We rescued as many people as we could. The most critically ill - but still moveable - patients were loaded into the handful of ambulances we had left and driven south at speed whilst the more mobile patients and the staff were herded into army lorries and evacuated. We couldn't save everyone, however. There were some just too ill, too badly injured. Some hooked up to various machines. Those people were each administered a lethal, but painless injection which killed them almost instantly. None of them knew what it was, which im thankful for. Whilst i know in my heart that my actions were the right, perhaps the only thing to do, killing a dozen pensioners and cancer patients in their hospital beds is not something anyone would ever want to live with. I had no choice though. Id heard the reports on the radio about other hospitals being overrun and bed bound patients being torn to pieces still alive and conscious. I refused to allow that at my hospital.

I made a choice.

I have to live with it.