Above the Wardour Street Starbucks in the heart of Soho, there's a compact, two-floor office with a busy reception, a small bar and a tiny lift. For all its charm, it's not where you would instantly expect to find the British Gas, Tango, Heineken and BT accounts.
But don't be fooled. In much the same way that a pea-sized black hole can effortlessly ensnare a passing star, this little office has the knack of sucking multimillion-pound accounts into its orbit.
At the corner of the building is an office shared by three men: Simon Clemmow, Johnny Hornby and Charles Inge. Since its launch two years ago, the agency that bears their names has, particularly in new-business terms, been more successful than even they could have hoped.
It's not just the volume of wins that has got the industry talking - it's the size of the accounts. CHI has taken business from big agencies, often breaking up long-term relationships in the process. The degree to which the agency has succeeded in this is unprecedented: for the two years CHI has existed, it has posed a major threat to the establishment. British Gas was yanked from BMP DDB after 12 years; The Daily Telegraph was at J. Walter Thompson for eight years; Expedia moved from Euro RSCG Wnek Gosper Partners and BT Yahoo! came from Abbott Mead Vickers BBDO.
It's tempting to credit this success to Hornby, CHI's managing partner.
As a skilled account man and a notorious schmoozer, he is the public face of the agency. He is incredibly well connected: the chief executive of Carphone Warehouse, Charles Dunstone, was the best man at his wedding.
Along with Peter Mandelson, Mirror Group's managing director, Ellis Watson, and others, Dunstone has a place on the agency's board. A mature board has helped CHI avoid the pitfalls faced by other start-ups. Clemmow says: "Dunstone often has Johnny coming back from meetings with his tail between his legs."
Hornby's evident affability is a serious business tool. There aren't too many people able to persuade three companies offering fixed-line phone services (BT, British Gas and Carphone Warehouse) to co-exist at a single agency.
If Hornby's strength is his power of persuasion, Clemmow's is his experience.
He has done the start-up thing before and this, coupled with a sharp brain, persuades potential clients that CHI is a safe pair of hands.
Inge completes the attraction. His quiet manner and famous snuggly jumpers make him approachable. He's not the volatile, capricious creative director that clients expect. That his name is intrinsically associated with the Every Little Helps campaign for Tesco from his days at Lowe is another key strength. Tesco is the success story that many clients would like to emulate.
You've only got to spend a few minutes with the founding partners to know that no one person carries the agency. The three interact effortlessly.
They expound the company ethos, that of the big idea, passionately, never interrupting or contradicting each other.
What is even more striking is that, despite the obvious differences in their personalities, the three clearly get on.
"Clients tell us that they like the fact that it's obvious we get on so well," Clemmow says. "At other agencies, I've been told that I was part of what looked like a slightly dysfunctional unit."
Clemmow's professional relationship with Hornby was born at TBWA\London.
Hornby explains: "TBWA is a fine agency but I enjoyed going off with Simon to do big idea awaydays with clients more than I enjoyed haggling over redundancies. Every time a pitch came in, we wanted to do it."
The two eventually left in the summer of 2001, taking the £10 million Carphone Warehouse account with them. Within a few months, they'd persuaded Inge to leave Lowe after 16 years. "I didn't know Johnny and Simon at all," Inge admits.
"Even when I read the coverage of the start-up, I couldn't put faces to their names."
The chemistry the three have since developed is certainly contagious and one can believe that clients are seduced by it. But surely there's more to it than that? Why are advertisers so willing to entrust their business to CHI?
Clemmow answers this question by handing me a slim volume, cutely entitled The Little Book of How We Work. To say that the CHI partners take this book seriously is to put it mildly. "This tells a client exactly what we will do between receiving a brief and coming up with the big idea," Clemmow says.
What is particularly interesting about this process is the level of scrutiny under which CHI puts prospective clients. All advertisers interested in CHI are subjected to both a "cultural audit", to uncover a brand's positioning and values, and an "ambition audit", a series of face-to-face interviews and questionnaires for all directors.
If, after this has taken place, the agency doesn't feel compatible with the advertiser, it doesn't pitch for the business. "We won't do any ads with a client unless we have agreed to work with them to try to uncover the big idea," Hornby says. "In that sense, clients select themselves.
We tend not to progress with clients who just want to start by saying 'will you do some new advertising for this brand?' We're much better with the clients who say 'my brand has got a few issues and we need a big idea to get it back on track'."
At the root of this process is the agency's reluctance to be treated as just a supplier of creative. While not every company shares CHI's esteem for the role of advertising, those that do are usually smitten with the agency by the time it comes round to pitching.
The partners cite their relationship with The Daily Telegraph as a good example of the CHI process in operation. The agency sat down with key Telegraph stakeholders, identified their main problem and produced not just new advertising, but a new positioning. And, love it or loath it, there's no doubt that the Bestseller campaign has the potential for longevity.
On the whole, CHI's creative work has received a lukewarm reception from the rest of the advertising industry. Perhaps it has been unfairly overshadowed by the agency's impressive new-business performance.
In its defence, CHI points to the gold award it won at this year's Cannes Festival for its campaign for Tango. The three partners also maintain that they would sooner come up with a big idea that can sustain a long-running campaign than a one-off killer execution that works in isolation.
Inge explains: "When we have an idea, we put it through the whole of a client's organisation. This is a huge job that cannot happen quickly. It's like a huge iceberg and the tiny little tip of it is the communications. But because that iceberg is going to last forever, the tips of creativity can come and go. You will get some good ads and some not-so-good ads, but the point is that creativity is just a bit of what we do."
To be fair to CHI, no-one could argue that its creative output has been poor - it just hasn't been as spectacular as Inge's reputation and the new-business league suggest it should be.
There can be no doubt that its campaigns for the likes of The Daily Telegraph, Carphone Warehouse and British Gas have laid solid foundations. But Hornby repeatedly cites Tesco's Every Little Helps and Heineken's Refreshes the Parts Other Beers Cannot Reach as the type of campaigns that CHI believes in. It's this combination of strategy and spark that the agency must aspire to.
As for the future of CHI, the partners are deliberately opaque on the issue. They talk about getting bigger and better and producing memorable campaigns and they see no reason why growth should dilute their culture.
But they choose not to dwell on matters of pure accountancy. It would be a remarkably lucky coincidence if all three partners had the same attitude to selling up, but all they will admit is that they'd sooner follow Bartle, Bogle and Hegarty's example than that of Rainey, Kelly, Campbell and Roalfe.
Clemmow - 47
Hornby - 36
Inge - 42
Clemmow - Marylebone
Hornby - Notting Hill
Inge - Barnes
Clemmow - Liz (wife), Nick (son, 14)
Hornby - Clare (wife), Ben, Arabella, Joe (children from first
Inge - Jane (wife), Sarah (daughter, 13), Emma (daughter, 11), Laura
Clemmow - "Litany", The Independent
Hornby - "Think different", Apple
Inge - "Fast talker", Federal Express
DESCRIBE YOURSELF IN THREE WORDS
Clemmow - Thoughtful, tidy, happy
Hornby - Little posh bloke
Inge - Homo sapiens (male)