"I mean, bridges are good fun but I think sewers have had the biggest impact on life. Clean water is the most important thing."
Fison is the new chief executive of Skanska Construction Group, the UK-based division of the Swedish multinational. He takes the place of Keith Clarke, who was promoted to the parent company's board in March.
The 50-year-old civil engineer admits that Clarke will be a hard act to follow. "I don't have the high profile of my predecessor," he says. "It's fair to say I'm not very well known in the building industry. I'm better known on the engineering side."
Fison has taken charge of a £1.4bn group employing 17,000 people. It includes Skanska UK, the fourth biggest construction concern in the country, as well as a global mining and gas specialist and a civils business in India.
Maple Cross House, the firm's suburban base near Rickmansworth in Hertfordshire, has undergone a lot of changes in recent years: it housed part of Trafalgar House's construction wing until that was bought by Kvaerner in 1996; the Norwegian contractor was in turn bought by Skanska in 2000.
Today, the building is a curious blend of Scandinavian cool and old-fashioned British austerity. The entrance is stylishly Swedish – light and airy with designer chairs and wooden flooring – but this soon gives way to a tatty warren of cellular offices.
The chief executive's lair, at the far end of an interminable corridor, is enormous, with a capacious power-desk, an antique dining table with matching chairs and a gigantic whiteboard on wheels for impromptu doodling. A Davy safety lamp sits behind his desk and a photo of a gigantic gas tank takes pride of place on the wall – clues to Fison's previous position as head of Skanska's gas and mining interests. Before that, he ran Balfour Beatty's rail and civils businesses.
Fison himself has the reassuring manner of a doctor and is wearing a red tie dotted with tiny monkeys. "The gas tank was good fun," he says. "They're 100 m in diameter; you could just about put the Albert Hall in them."
His predecessor has left him a business in fine shape after a shake-up that replaced the Kvaerner structure with one in line with the Skanska model. "Skanska's philosophy is to develop strong local businesses, so that's what I'm concentrating on doing."
The Swedish parent had problems last year, particularly in Poland the USA and the Nordic countries. An aggressive growth push ran smack into the global downturn and 11 September with the result that profit went into freefall and 3500 staff lost their jobs.
But Fison insists his group is thriving. "We're having a good run; we've been hitting our budgets consistently for three years," he says, adding that "objective number one" is for the firm to continue being "boringly predictable".
Yet Fison also has to come up with new ideas if he wants to keep the people in Stockholm happy, and the PFI is at the heart of his plans. Skanska already has work in progress worth £560m in the defence, health, education and custodial sectors and he is hunting aggressively for more contracts.
If you’re a hospital and you’re given the choice between a startling front entrance and 20 more beds, what would you choose?
"PFI is a big, big play as far as we're concerned. It accounts for about 30% of our building work and is growing."
Fison's way forward is to emulate the big PFI players and develop in-house expertise in every aspect of the PFI. To target hospital jobs, for example, he is hiring everyone from senior architects to experts in medical equipment maintenance.
"If we're bringing in medical equipment, it's not good enough to simply say we'll go and get it from a medical equipment manufacturer," he says. "Do we know we've got the best value equipment at the right price? And are we going to be able to maintain it? We need to have expertise in these areas. You'll see us move further that way because we need to be able to project manage not just the building end of it but the totality. And we're going to put more effort into that than anybody else."
Fison is a big fan of the PFI; he refuses to grumble about the tortuous bidding process ("It's a fact of life – live with it") and disagrees with critics who have slated the design of the early PFI hospitals. "If you're a hospital and you're given the choice between a startling front entrance and 20 more beds, what are you going to choose? You need to remember that this is taxpayers' money and what we actually want is an efficient health service."
He also believes that the PFI is changing – for the better – the way the industry operates. By forcing teams to come together to consider a project holistically, the PFI is fostering the development of integrated teams in which different disciplines co-operate fully. "It changes the nature of contracting. That in turn will affect the way we do other jobs."
Take, for example, the relationship between a contractor and an architect on a typical design-and-construct project. "They speak different languages," he says. "The likelihood of getting clear communication is very low. We've got to remove that barrier and get them speaking the same language."
To that end, Fison is giving 600 of his staff design training so they can better understand what the architects are talking about. "If we train those working on design-and-construct jobs to understand the issues as the designers see them, you will resolve problems much more quickly."
He is also sending Skanska staff to work in the architects' offices. "That's partly to facilitate and partly to coach: to say, 'that doesn't work for us', 'that's going to be very expensive' and so on."
Teambuilding is a theme Fison returns to again and again, but it's clear that his agreeable, engineering-buff mien conceals the ruthlessness and obstinacy needed to succeed at this level. "I'd say I'm pretty easy-going, but also quite enthusiastic about things," he offers, when asked to describe himself. But Skanska's candid press and publicity boss Cheryl Eaton, who is sitting in on the interview, begs to differ. "Easy-going? I'd question that," she pipes up. "Ooh," Fison replies in pantomime disagreement: "I am!"
But Eaton stands her corner: "I'll get a rude note saying, 'Cheryl, what have you done about this?' Oh yeah, David's quite clear what he wants. He's nice to work with but he can be slightly bullying."
Fison showed his ruthless streak immediately after his promotion when UK building managing director Andy Sturgess suddenly left the company. Was he pushed? "No, no.
He had done a great job turning the business around, but I decided we needed a slightly different approach. It was a difference of vision. It was my decision."
Personal effectsWhere do you live?
Herne Hill in south London with my wife and two kids. It's a fairly straightforward house. I built a flat alongside it where my mother-in-law lives. She either had to move into a home or come and live with us. I think that's a fairly easy decision to make.
What do you do at the weekends?
I have a house in Suffolk I run away to. It's an old school in the middle of nowhere. I patched it up from nothing. It's a bit jerry-built, a bit shambolic, but nice and comfortable. We don't have a TV but we do have a phone, regrettably.
You're wearing Jaguar glasses. Is that what you drive?
No, I drive a four-year-old Mercedes E230. I don’t know about the glasses; they were probably the cheapest in the shop.