Then came 2006. Owen and Laureys were trying to find a reliable way to communicate with patients in a vegetative state, including Gillian. In July 2005, this 23-year-old had been crossing a road, chatting on her mobile phone. She was struck by two cars. Yet, though she had been diagnosed as vegetative, there was something about her that caught the attention of Martin Coleman of the University of Cambridge Impaired Consciousness Research Group, who submitted her for study by Owen.

Five months later, a strange stroke of serendipity allowed Gillian to unlock her box. The key arose from a systematic study Owen started with Laureys in 2005. They had asked healthy volunteers to imagine doing different things, such as singing songs or conjuring up the face of their mother. Then Owen had another idea. “I just had a hunch,” he says. “I asked a healthy control to imagine playing tennis. Then I asked her to imagine walking through the rooms of her house.” Imagining tennis activates part of the cortex, called the supplementary motor area, involved in the mental simulation of movements. But imagining walking around the house activates the parahippocampal gyrus in the core of the brain, the posterior parietal lobe, and the lateral premotor cortex. The two patterns of activity were as distinct as a ‘yes’ and a ‘no’. So, if people were asked to imagine tennis for ‘yes’ and walking around the house for ‘no’, they could answer questions via fMRI.

Gazing into Gillian’s ‘vegetative’ brain with the brain scanner, he asked her to imagine the same things – and saw strikingly similar activation patterns to the healthy volunteers. It was an electric moment. Owen could read her mind.

This is insane.

“This is your big chance. Just do your best.” Owen gazed down at 39-year-old Scott Routley, lying on a gurney. Scott had studied physics at the University of Waterloo, Ontario, but his promising career in robotics came to an end when, aged 26, he collided with a police vehicle. Since that accident, on 20 December 1999, Scott had been diagnosed as being in a vegetative state by a well-seasoned neurologist, Bryan Young, and in 2012 his diagnosis was confirmed by Owen’s team, again using traditional methods.

As Owen talked to him, Scott’s mouth remained wide open, apparently unaware, the same way that he’d been in the 12 years since the accident. This encounter was filmed by a crew from the BBC. Reporter Fergus Walsh was there to witness the moment that Owen attempted to reach inside Scott’s mind. Owen admits now that he was sceptical that the scans would reveal anything at all.

The team scanned Scott several times. To their surprise, the pattern of brain activity showed Scott knew exactly who he was, where he was and that he was actively choosing to answer the team’s questions. “My heart stopped when we asked if, after 12 years, Scott was in pain,’’ Owen recalls. “Thankfully, the answer was no.”

I had no idea EEG was even close to this level.