By Jeremy Scott-Joynt
BBC News business reporter
Of all the things to expect when walking into search giant Google's London office, a three-piece suit is not high on the agenda.
Vint Cerf is one of the 'fathers of the internet'
But if your job title is Chief Internet Evangelist, perhaps you should dress up a little.
The gentleman sitting across the table in the smart tailoring, with a slight stoop and a neatly-trimmed grey beard, is Vint Cerf - one of a small group of people widely regarded as the inventors of the internet.
Birth of the network
"Evangelist" as a title was Google's idea, not his. "I wanted Archduke, but they said no," Mr Cerf says.
But the infectious enthuasiasm bubbling off him certainly justifies the title on the business card.
If Google were looking for a card-carrying example of its corporate motto, "Don't be evil" - a motto which is increasingly coming under close scrutiny now that Google is a $100bn public company - it could hardly do better.
After all, Mr Cerf was was one of two people responsible in the 1970s for coming up with the language by which internet traffic communicates.
The decision to throw the details of TCP/IP, as it is known, open to the world is what has allowed the network to flourish and grow into what we know as the internet today.
Who pays whom?
It comes as little surprise, therefore, that the question of who controls the network is still at the top of his mind.
VINT CERF: CAREER HIGHLIGHTS
1976: Worked at the US Department of Defense Advanced Research Projects Agency (Darpa). Co-developed TCIP/IP with Robert Kahn
1982: Joined telecoms firm MCI and developed MCI Mail, the first commercial email service to be connected to the internet
1992-1995: Founding president of the Internet Society
1994-2005: Returned to MCI as senior vice-president to guide systems design and technology strategy
1997: With Robert Kahn, awarded US National Medal of Technology by President Bill Clinton
1999: Joined board of the Internet Corporation for Assigned Names and Numbers (Icann), in charge of the internet's domain name system
2004: With Robert Kahn, awarded the ACM Alan Turing Award - dubbed the computing industry's nearest equivalent to a Nobel prize
September 2005: Joined Google as Chief Internet Evangelist
November 2005: With Robert Kahn, awarded Presidential Medal of Freedom by President George W Bush
And right now, there are one or two big companies whose behaviour is causing him no little concern.
Not Google, of course, whatever some of the company's detractors - and their numbers are growing - might say. And not Microsoft either.
No, it's the US telecoms companies he believes want to impose "toll roads" on the internet.
Firms such as AT&T - currently attempting a merger which could leave the whole of the US with two dominant telephone giants - argue that Google and other similar companies are getting a free ride.
A senior AT&T executive recently warned that the search giant and its software and services rivals needed to be ready to start paying their share of the cost of providing businesses and consumers with access to the internet.
"He said Google's getting a free ride," Mr Cerf says, with dismay.
That way, Mr Cerf believes, disaster lies.
It would certainly be bad news for Google, whose entire business model - selling adverts, and the provision of adverts, to whoever wants them - is predicated on easy access to any website, by anyone, anywhere.
But everyone else would suffer too, he says.
"All the new applications have showed up because no-one's had to ask permission," he insists.
Google's 'don't be evil' motto has come under fire
But wouldn't it cut down on the competition? After all, not everyone is as rich as Google.
"It's not altruism," he says. "We can generate additional revenue for both of us."
Another threat - one from which carriers are backing away - is to selectively slow down traffic of companies offering services that the carriers themselves sell.
Mr Cerf would quite like to see legislation to stop this kind of thing on anti-competitive grounds.
One might argue that this is hardly the classic call of the traditional internet libertarian.
But underneath the corporate chatter lies the old siren song of internet evangelists - whether freelance or on the books of a $100bn corporation.
Free up the network - both in price as well as access - and everyone will be empowered to build exciting, innovative applications at the edges.
As the amount of information that can flow to end users expands, from dial-up modems to DSL lines to the kind of ultra-fast, 100-megabit-per-second access enjoyed by some consumers in South Korea and Japan, then Vint Cerf argues that the exciting services will follow.
And if carriers try to set up pay-per-view barriers between users and the big, wide world, they will only end up harming themselves by cutting back on people's reasons for buying internet access through them.
This picture has some big organisations running scared.
Vint Cerf told Congress about his disdain for telecoms carriers' plans
On the one hand, newspapers are casting about for ways to avoid the Web wiping out their sources of revenue.
Some blame the blogs, some say that the taste for "free stuff" is too ingrained among online readers.
Broadcasters are worried too.
Designed for the world of "appointment-to-view TV", what are they to do when the time-shifting world of personal video recorders becomes the norm? When users can download an hour-long programme in a tenth of the time it takes to watch?
Pretty soon schedules and channels will seem as quaint a throwback as black and white sets and laserdiscs.
The way Vint Cerf sees it, though, this focus on the threat means firms are missing the opportunities.
"The download is just a stream of bits, after all," he says. "And you can deliver all kinds of ancillary information - and adverts - alongside it."
He imagines a world where the TV picture comes with a toolbar, or a range of icons, where it's perfectly normal to pause the picture while you look up a bit of information - or buy products placed onscreen.
And as for the print world - well, Google believes it has answers there too.
As the acknowledged world expert on targeting ads, why should the firm not bring its skills to bear on putting, say, individually chosen adverts into subscribers' magazines?
Google going offline. Stranger things, perhaps, have happened.
So are the traditional publishers and broadcasters ready for this new world?
"Newspapers are online... and they're learning all kinds of things about their readers that they never could have known in print. There's no reason they can't use that to their advantage."
And the broadcasters? Well, they - it seems - are not quite ready for the revolution.
"I don't see much attention being paid in the traditional broadcasting industry."
Out of this world
Whatever the outcome of the lightning-fast evolution still under way online, one gets the impression that Vint Cerf's innate optimism will remain undimmed.
Somehow he has navigated through three decades of online activity with his enthusiasm intact.
Perhaps that is thanks to little projects like the "interplanetary internet" - extending the network out into the Universe, via satellites and space probes.
Nasa's Mars Orbiter, for instance, carries equipment designed to make the "InterPlaNet" possible.
"Some people believe we're building an interplanetary backbone and they are hoping someone's going to come," Mr Cerf says.
"That's not what we do."
Perhaps that dream is off the table. But talking to Vint Cerf, it's difficult to imagine many that are.