It might look like a scene from a science fiction movie but it’s very real – and it’s on our doorstep. Deep in The Royal Free Hospital, through a maze of corridors and up and down two lifts, is the only high security isolation unit in the country.

If that sounds high-tech, that’s because it is – two beds covered in plastic tents with their own air supply take up the space of a ward that would usually hold more than 20 patients, to treat the most infectious diseases in the world.

Diseases such as ebola and lassar fever are rare in the UK and cases are usually contracted abroad.

But two weeks ago the first confirmed case of Crimean-Congo haemorrhagic fever hit our shores.

A man returned from Afghanistan with the disease, which has a 30 per cent mortality rate and is highly infectious.

The 38-year-old, who died a few days later, was transferred to The Royal Free via an RAF military jet where he received treatment in an isolated tent bed, allowing specialists to care for him at close range.

The previous time the high security unit had been used was in 2009 after a case of lassar fever.

Dr Michael Jacobs, an infectious disease specialist, said they have to be ready to swing into action at a moment’s notice.

“The people who are really at risk from this are the health workers and laboratory staff who are handling the specimens from a patient,” he said.

“These things are mostly transmitted by blood and body fluids – it could be a splash in the eye.”

“Everyone has to be geared up and ready to open a ward which otherwise is not used and they have to do so without causing risk to themselves.

“There are protocols for the simplest things, such as provisions of food or medicine from the pharmacy.”

The ward has a one-way flow of air, people, food and waste, and doors lock automatically.

The ward also has three large ‘auto-claves’ or incinerators that safely dispose of all waste from the patient which is heat-sealed in plastic so it is never exposed to the outside world.

Every time a patient passes through, a new, bespoke, high security isolation tent – with built-in suits for doctors including a cooling pack so they don’t sweat too much – has to be made.

“Every time we have a patient we have to destroy the tent afterwards,” Dr Jacob explained.

“The room used by the patient who had Crimean-Congo haemorrhagic fever hasn’t got a tent on it because we had to destroy it afterwards in order to make it safe again.”

The unit opened at The Royal Free in 2003 after moving from Coppetts Wood Hospital near Muswell Hill.

Dr Jacob said: “Because of the amount of travel in and out of the south of England and in London it makes sense for the unit to be at The Royal Free because the less travelling, the better.”