Interview: Liam Fox

"Dear Liam," Liam Fox says. 'Please say that again,' the computer tells him. "Dear Liam," Liam Fox says again. This is getting weird now. 'Please say that again,' the computer tells him. "It's not working," the man formerly in charge of Britain's military mutters.

Out of all the strange political interviews I've done, this ranks highly among their oddest moments. Fox has been brought low. For a man who spent 2010 reshaping Britain's armed forces, with the might of the Ministry of Defence behind him, things have come to a pretty pass.

But this is not a man who looks like he is in the wilderness. He has used his time out of power – his October 2011 resignation ended 17 years of frontbench politics, so he'd earned a bit of a break – to write a new book. Politicians think tactically, he explains. They rarely bother to look beyond the next general election, or even beyond what's happening tomorrow afternoon. This project, the product of a series of interviews with giants of world politics like Henry Kissinger, Bill Gates and even Tony Blair, is "a chance to think strategically" about the biggest issues this planet faces.

In fact 'written' is not the right word, because 'spoke' into his voice recognition software would be more accurate. Who needs pesky assistants when you can simply dictate it into a machine? After his brush with the civil servants at the MoD, this might come as something of a relief. It might not have worked in his little demo for me – it turned out eventually something or other hadn't been switched on – but it has certainly done the job in helping him produce the 370 pages of Rising Tides, published by Quercus and in all serious bookshops in exchange for a £20 note.

"I've found the period being out of government extraordinarily refreshing," he says.

"I used to tell my patients the time when you think you simply can't afford to go on holiday is when you most need one… I have found it extraordinarily valuable, as well as enjoyable, to be able to stand back and say 'what do I actually think about the way the world is developing and Britain's role within that?'

His answer, I put it to him, is that Britain needs to continue its centuries-old tradition of punching above its weight. "I hate the phrase 'punching above our weight'," he says quickly. "It tends to be used when you're trying to get things on the cheap." Britain has the world's fourth largest military budget and the sixth largest economy, after all. "We're hardly a midget in global terms, and with that comes responsibility."

The appearance of his first book shows Fox remains active, engaged and eager not to step back from the world stage. If Cameron ever gets round to his reshuffle there is a decent chance he will use the opportunity to bring the man who came third in the 2005 leadership contest back into the fold.

Fox remains well-respected in parliament by his opponents and liked by many in the party. I wasn't impressed by his apology to the Commons over the blurring of personal and private which contaminated his relationship with lobbyist Adam Werritty and led to him losing his place at the Cabinet table. Fox's own memory of that sad afternoon in the Commons is of the support he received at the time: over 100 MPs penned friendly little notes to him afterwards. The bruises are still there, but are fading slowly.

"I thought if you're unable to do your job then you resign, you make your case and, if you want to, come back," he says. So I press him a little more directly – and he makes clear he would return if asked. His main aim, he explains, is "to see a majority Conservative government elected". This is of interest, because he could well be in line for the chief whip job – a tough gig at a time when Conservative rebels have never been more empowered. "I want us to put into place a programme that offers the wider values of conservatism," Fox declares. His right-wing credentials would make him a formidable candidate for the job, allowing him to talk to the backbench grumblers on their own terms.

It might also be more appropriate than the alternative expected vacancy in international development, where Justine Greening is widely expected to be on the way out. Fox has been a consistent critic of the aid agenda both in and out of government. And his recent deep thinking about the issue has not changed his views.

"I'm not sure how important it is in giving us influence unless we're very willing to attach strings to it," he says. "I think it's something we should be making very clear as part of our willingness to give aid, that we expect certain values to be upheld. One of the things we should be doing with aid is ensuring the values we have, that we believe will lead to a better life for ordinary people, are applied as widely in the globe as we can." If by some extraordinary twist Fox does find himself tasked with marshalling the UK's aid spending, his department will be in for quite a shock.

It was an experience the Ministry of Defence suffered back in 2010, when Fox arrived in a department grown somewhat complacent under 13 years of New Labour. Fox had to take the department by the hand – the way he tells it, even working out a template for how you might go about running a decent strategic defence and security review (SDSR) seemed beyond the capabilities of his civil servant assistants. He shows me the notebook from one of the early SDSR meetings. It's an A5 book turned landscape, with Fox's scribbled handwriting sketching out how each change in the balance of Britain's military ought to be assessed. He seems thoroughly proud of it.

Two years since leaving power, Fox is already thinking about the dilemmas which will face the next defence review, now just a couple of years away. He expects cybersecurity to get more funding – and believes manpower questions will be critical. Surely the numbers can only go down, not up, given the cuts being made at present? "It's not simply a question of numbers, it's a question of where your strength goes," he says.

"For example, I think we'll need to see growth in the manpower available to our surface fleet as we start to increase the size of that again. Therefore balancing that with a reduction in the size of the Army is something that makes sense. But that's not without its challenges in terms of regulars vs reserves. That's a very big issue that needs to be tackled."

There are even bigger issues facing Britain in the coming years. He applauds the pivot towards the Gulf already underway, but also thinks we need to pay more attention to the South Caucasus and the High North. The Arctic is not about to become the next Mediterranean, Fox says, but it bothers him all the same that a reason so rich in resource potential is bordered by Russia and four major Nato powers.

What it all boils down to is influence. It's why Fox believes Britain has to continue having a strong voice in the global debate. "Of all the times when you could consider opting out, this is the least credible of all of them, historically," he says. He's talking about the last 500 years, not the last ten or 20. Globalisation is a key theme of his book and, as he points out, these forces are there whether we want them to be or not. "Britain faces a simply binary choice: we're either going to shape the world we're in or we're going to be shaped by the world we're in. That's it."

Influence is a product of power. Or as he puts it: "I think people who are in positions of power have an ability to project an agenda." Fox believes Britain ought to have this. So it's no surprise that, having been away from power himself for two years, he now believes the time is right for a return.

Rising Tides might sell a few copies and has been a useful exercise in strengthening Fox's claim to be a deep thinker. Its author must surely believe it is no substitute for actual sway, though. "If the prime minister asked me to rejoin his government," he says openly, "of course that's something I'd give serious consideration to."

Rising Tides: Facing The Challenges Of A New Era, by Dr Liam Fox, 327pp, is out now, published by Quercus, is available as a hardback (£20) or e-book (£14.99)