THE makers of documentary series Hospital were just a couple of days into filming at St Mary’s Hospital in London when phones began going off at a meeting they were recording.

Calls and news alerts were coming through of an incident at Westminster Bridge. Details were limited, but some of the casualties were on their way.

In the first episode, we saw staff at the hospital immediately set about preparing to receive the injured, cancelling non-emergency surgery and seeing if any beds can be freed up.

The first casualty to arrive, it later turns out, is Khalid Masood, the attacker who drove at pedestrians on Westminster Bridge and stabbed Pc Keith Palmer before being shot by armed police.

We see Masood, whose actions caused the deaths of five people, stretchered into St Mary’s in Paddington. Shortly afterwards, a member of staff says: “The first one is RIP.”

Seeing the killer on screen is unsettling viewing, but Simon Dickson, of programme maker Label1, insists it was important to include.

“He’s part of the story, and his appearance in the film is as you see it. It’s brief, but his arrival is a key part of the day, and that is fully reflected in the way that scene is handled.”

The BBC Two show is now in its second series following the Imperial College Healthcare NHS Trust. Having an established relationship between hospital staff and camera crew meant they were allowed to record the events unfolding on March 22.

“The team were all profoundly shocked by it, but we, I guess in the same way that the hospital team do, go into a form of autopilot which is to faithfully document what’s going on around us,” Dickson notes.

“We’ve ended up through our partnership with Imperial with a piece of television which is very much about now, modern Britain and the kind of things that unfortunately do go on within it.”

It’s also, as Dickson notes, “a piece of television that’s a powerful testament to the human spirit”, as we follow the progress of three of the injured victims and the outstanding care they are given at the hospital.

We meet 16-year-old Victor, who was on a school trip from France when he was struck by the vehicle on Westminster Bridge. His injuries include a potentially life-threatening collapsed lung.

Victor’s friend, 18-year-old Yann, requires surgery on his scalp and has spinal damage.

Meanwhile, 40-year-old British man Stephen was on a birthday excursion when he was hit, and suffered multiple injuries. His wife was next to him and escaped with minor injuries, but she is devastated for her husband.

We watch the victims undergo life-saving surgery, and begin the healing process under the expert care of the team at St Mary’s.

Alongside the physical wounds, however, they will also have to live with the emotional trauma of what has happened to them.

It’s a very emotional episode, but Dr Alison Sanders, clinical director at Imperial College Healthcare NHS Trust, explains that when there’s a job to be done, “you just get on with it”.

“You don’t really process the emotional side, you don’t allow yourself because you don’t have the time to do it, you’re just so busy,” she adds.

“None of us really knew what had happened until the end of the day, until it was all over and you went home and turned the television on.”

Dr Sanders admits that some members of staff were sceptical when filming began on the first series last year.

“There are always a few people who don’t think it’s a very good idea and it’s not what we’re there for, we’re there for healthcare,” she says. “Understandably the first week of filming of series one, I think people were fairly anxious, but we built up relatively quickly trust between the camera crews and producers we got to know...

“It all worked very well and the end product of series one was so fantastic and so well-received by everybody because it just showed it how it really is, so everybody was far more confident going into series two.”

Later in series two we will also see the Trust deal with patients with dementia and psychiatric episodes, and learn about how some patients are paying for parts of their medical treatment privately.

The whole show, says Dr Sanders, is an opportunity “to demonstrate to the public what their NHS does and why some of the decisions that are made are so complex and difficult”.

Despite the challenges, it also reveals just how remarkable the NHS is when faced with a challenge such as the Westminster Bridge attack.

Dr Sanders adds: “We have to do something entirely different with zero notice, and you see everybody just switch into it, and then the following day we have to go back to normal because the work is still building up, the ambulances will still be coming in, as soon as we open the doors again, the floodgates open.”

Hospital returned to BBC Two on Tuesday June 20. Watch on catch-up via BBC iPlayer. The second episode airs at 9pm on Tuesday.