Underestimate Mike Cooper at your peril. That's the clear consensus that emerges when you talk to those who know him. And, yes, it's easy to see how it could happen. For a start, he looks like an accountant, a bland corporate man. He often comes across as a genial old-school bank manager.
And then there's the Hong Kong angle. Back in the days when sinecures in the Crown Colony were seen as a somewhat cushy number, there was an almost unthinking assumption that ex-pat executives who'd built their careers and reputations entirely in the Asia-Pacific market tended to get the shock of their lives on returning to London.
The theory has been more than a little dubious for a good few years now - but still, even in recent times, there have been one or two conspicuous examples of Far East stars who've burned up on re-entry.
And then there are those who assume, rather patronisingly, that Cooper has engineered a return for the wrong reasons. When the eldest of his two sons reached secondary school age five years ago, his wife and children began relocating to England during term time.
In the past few years, Cooper, so the gossip goes, has been angling for the right sort of opening to return family life to a simpler footing back in London. When David Pattison, the PHD founder and the architect of its nascent global network, decided it was time to move on, this was surely a mutually promising opportunity - Omnicom gets a safe pair of hands on the PHD tiller and Cooper gets to come home.
Cooper, 46, will become the chief executive of PHD Worldwide, with Barry Cupples, the chief executive of OMD in Central and Eastern Europe, moving across to replace Cooper as the chief executive of Omnicom Media Group Asia.
One rival network boss could barely disguise his glee last week. He confided: "We assumed that Omnicom would see Pattison's departure as a real opportunity. Pattison had a powerful vision, but he wasn't the right man to take it forward, so the PHD network was starting to seem very much like a second-string network used only for conflict resolution. We thought they'd do something inspired, like putting someone with a strong planning background in there. Our view of Cooper, quite frankly, is that he's a suit who won't really make a difference."
The counter-argument put forward by Omnicom sources is that Cooper is actually a formidable operator who has worked wonders in the Asia-Pacific region, and who has (almost as importantly) built himself a strong power base at Omnicom headquarters in New York.
He has, for instance, sat on the OMD Worldwide board for a number of years now and is a close ally of Daryl Simm, the chief executive of Omnicom Media Group - to whom he will, as in his previous role, continue to report.
He is, some say, hard-wired into the company now. "He knows where all the bodies are buried," one source says. "In a world where there's a decreasing amount of genuine senior talent in media, the organisation would have done almost anything to keep him."
And his supporters say he's actually perfect for the PHD job, which at this stage needs the quiet assurance and nurturing common sense that is Cooper's forte. But there's no escaping the suspicion that it remains a huge logistical challenge.
Currently, it comprises four separate bits: the UK agencies; the US agencies; the Asian network, which is a rebadged Omnicom regional network previously called Media Wise; and a handful of newly constituted European offices (predominantly formed by reallocating resources and people from OMD).
The picture is fragmentary to say the least, and the most worrying dysfunction is to be found in the US, where Omnicom Media Group doesn't really exist - there seems to be no co-operation between OMD and PHD at all and little co-operation between PHD North America and the rest of the network.
But these are, some say, exactly the sort of internal knots that Cooper excels at untying. "He's very personable, he understands politics," his friend and former colleague Charlie Varley, now the planning director at MediaVest Manchester, says. "He really gets on with people and he understands cultural nuance. You can't succeed in Asia, where culture is everything, unless you're very good at that. If you can master that out there, you can apply those skills anywhere."
Omnicom sources also point to Cooper's breadth of experience. He was one of a number of Saatchi & Saatchi media department executives who opted not to become part of Zenith Media when it absorbed the department. He initially moved to Hong Kong to become Saatchi & Saatchi's media director, but successfully made the transfer into general agency management, becoming the managing director of Saatchi & Saatchi Advertising Hong Kong in 1990.
He then had a successful spell on the media owner side with CNBC, as the distribution, marketing and ad sales director for the Asia-Pacific region, before joining OMD to launch its Asia-Pacific network from scratch in 1997.
In recent years, in addition to his regional role, he has headed a global accounts programme, looking after the likes of McDonald's, Nissan, PepsiCo and FedEx on a worldwide basis.
Characteristically, perhaps, Cooper was reluctant to talk to Campaign until all the clauses of his contract have been approved, so we don't have his take on the challenges ahead. So cautious is he, in fact, that he was pleading last week with his many friends in the business not to share too much in the way of colourful anecdotes. A refreshing change, you could argue, from the sorts of extroverts that encourage their mates to do exactly the opposite.
It's clear, though, that we can expect PHD to drop any pretensions to the sorts of quirkiness that Pattison wanted to retain as part of the PHD heritage. Cooper's appointment is recognition that you can't be both a network and a media boutique. The goal will be to create a global network that will be the equal of OMD. Different, yes, but not too different.
But those who know him say that his focus won't be entirely structural and inward looking. "He is great at new business," one source says. "And he is very, very good with the senior clients. Yes, he's corporate, but so are the sorts of clients who want global media networks."