Five years ago, Rob, a 38-year-old father of two, was fitting kitchens and bathrooms for a living. Now he is a digital spy. As one of GCHQ's army of cyber analysts in the United Kingdom, he monitors global counter-intelligence targets in countries he cannot disclose for national security reasons.

"You're always looking for that key or that nugget that's going to really help progress the operation," he says, before adding proudly that his work often makes the headlines. "I could be having my tea at home, and the news will be on, and I want to turn around to my wife and say, 'I helped on that one.' It feels great. But then you realise you can't share it with anybody outside of work."