As we sit down for the interview, Brain clears aside the maps sprawled across his drawing room table - there to cement his passion for sailing and prepare him for his Royal Yachting Association skipper's navigation exams.
Brain is at the end of his three months' gardening leave from Weber Shandwick as we meet. He started work as Edelman Europe's helmsman in mid-December.
As well as pondering various maps, he has been readying himself for his pan-national responsibilities with an intensive French course. 'My (comprehensive) school allowed me to opt out of languages after just two years at 14, which I did and it was a crap decision,' he recalls. 'It seems a tad English to presume you can run communications in a region where you make no effort to understand the language at all.'
The Edelman job offer was straightforward - he got a call in the summer from president and CEO Richard Edelman, to whom he reports.
'My time at WS has been the three most challenging years of my career,' says Brain. 'Everyone thought Colin (Byrne, the other joint UK chief executive) and I would fall out, but we got on like a house on fire. Weber Shandwick CEO Harris Diamond made the fudge decision of not choosing a sole UK chief, so at some stage one of us would have to leave to give the other room.'
Brain's prime task at Edelman is to bolster its consumer and tech practices.
'Edelman has to be stronger in consumer and tech to boost the whole network because, unless you win those accounts, chances are you will be working as a group of individual offices rather than as a networked business,' he says.
On the consumer side, the agency has been eyeing up potential acquisitions.
Indeed, Brain's credentials are strongest in consumer PR and brand development.
After a six-year stint in the Far East that included an in-house role at Visa International, Brain spent two years heading Burson-Marsteller's marcoms practice, before becoming UK chief exec at BSMG Worldwide, responsible for 200 staff. The subsequent merger into WS carved up the various practices with Byrne, leaving Brain in charge of the visual communication, tech, healthcare and consumer divisions at the UK's largest agency.
The Edelman role sees him manage 350 people across 10 countries with fee income close to £30m.
Byrne says: 'David's an assiduous networker and a creative thinker but he can get frustrated with process. At Edelman, he will have to be careful balancing what he likes doing with what his boss expects him to do, which is to kick ass and increase margins.'
Brain says his biggest mistake was down to overlooking his more prosaic responsibilities. It involved a WS practice chief hire who didn't last long. '(The person) interviewed brilliantly and the chemistry seemed right.
But I didn't do enough background checking. It's easy to get carried away with your instincts.'
When asked what irritates him, Brain says: 'People who think you can run a business on evaluation and process. We sometimes forget that the lifeblood of our industry is ideas. If you've got the right ideas, the rest takes care of itself.'
Brain, 41, describes his entry into PR as a 'distress purchase'. He took a PR job in his early 20s to fund his journalist training, but reporting on 'dog shows, and Womens' Institute meetings' for the local press put him off journalism.
Aside from sailing, Brain is passionate about Manchester City, to which he can't resist applying branding insights. 'The manager Kevin Keegan is fantastically on-brand for the club - he's always nearly got there but not quite.'
Ex-colleague Stephen Whitehead, now Allied Domecq group corporate affairs director, says: 'David has a strong marketing sense and an international outlook. But he's excitable. There's an element of the wild-child about him.'
While he doesn't volunteer it himself, there is a consensus that this wild-child tendency means Brain will stay at Edelman no more than two years and intends eventually to move with his Kiwi wife and five-year-old daughter back to the Far East. He does say: 'I imagine this will be my last agency job. Who knows?'
1984 Account manager,David Sheppard & Associates/
Trainee reporter, Newcastle Evening Chronicle 1986 Board director,
1992 Head of corporate affairs, Visa International, South East Asia
1998 Managing director, Burson-Marsteller, London
2001 Joint chief executive, Weber Shandwick UK & Ireland
2003 European president and CEO, Edelman Europe