Steve Blamer is arguably one of the most successful executives in the advertising industry. As president and C.E.O. of FCB Worldwide, he helped lead the 2006 merger between his agency and Draft Worldwide. The combined company, DraftFCB, had 9,000 employees, boasted S.C. Johnson & Son and Yum Brands as clients, and generated global revenues of $1.25 billion last year. Before his stint at FCB, Blamer was C.E.O. and president of Grey North America, another megabrand in the ad biz.

So in a business where image is everything, why has Blamer now relegated himself to a shared midtown Manhattan office space with rented furniture, just down the hall from a nonprofit and a pharmaceutical-industry recruiting firm?

As Blamer tells it, he is exactly where he wants to be. Last month, he became the first C.E.O. of the new American arm of Creston, a relatively small British holding company that owns an ad agency, a public relations firm, market research providers, and other marketing service businesses. He’s charged with building the U.S. business from nearly scratch and has been given $100 million to roll up advertising and marketing firms. The goal: to seize a chunk of the $149.6 billion American ad market, according to TNS Media Intelligence.

“You can’t get more entrepreneurial than this,” Blamer says. “It’s me, Angela [his longtime assistant], phones, and the ability to have a clean sheet of paper without all the legacy issues and problems you have when you go in to run a company of the size that I’ve run in the past. We can create something here.”

Sure, it doesn’t sound all that bad. But Blamer’s optimism may obfuscate how he ended up at his new job. Despite being one of the principal architects of the DraftFCB merger, Blamer ultimately left the resulting company. After recommending that Howard Draft, his counterpart at Draft Worldwide, take the helm, Blamer had expected to take a place as second in command. But soon, he says, it became clear to Michael Roth—the C.E.O. of Interpublic Group, the holding company that owns both Draft and FCB—that Blamer and Draft just couldn’t work together. According to Draft, “Steve and I had different visions for the future of DraftFCB.” Blamer tells a similar story. “We had different values when it comes to business,” he says. Ultimately, Blamer admits, “I was asked to leave.” His departure followed the official announcement of the merger in June 2006.

A 25-year veteran of the advertising business, Blamer had been C.E.O. of FCB for a year. Upon leaving the firm, he found himself at a crossroads. He took a vacation to Hawaii with his wife. He went on a few job interviews and decided to consult. But then in November, he had breakfast with Don Elgie, the C.E.O. and founder of Creston, at Elgie’s hotel room at the Carlyle in New York. The meal, which consisted of a single bagel, yogurt, and fruit, lasted five hours as Elgie elaborated his view of Creston’s expansion into the U.S. advertising market.

On a napkin, Elgie began to draw a pyramid: At most holding companies, he told Blamer, the point at the top—the holding company—is the center of attention. But Creston flips that concept on its head by putting the holding company organizationally below its firms, making Creston entities the stars rather than Creston itself.

Additional talks followed over weeks and months, but Blamer was sold. Less than six months later, he was setting up temporary office space and plugging in a phone. Creston’s stateside arm was in business.

And what business is that? For now, Creston U.S. is in the acquisitions business. Blamer has his eye on ad agencies, public relations firms, market research experts, and digital- and interactive-advertising specialists. As the company’s goal is to provide a full range of marketing services, Blamer is entertaining all possibilities. His acquisition targets would ideally have a minimum of about 50 staffers, will have already met profitability targets and shown tremendous growth, and would have owners who want to stay involved in the company.

In his month on the job, Blamer has already approached a handful of companies and expects to announce his first deal within a year.

It may seem that Blamer is in an enviable position, but he has a long way to go before he cracks the American ad market. The leading holding companies—Omnicom and WPP Group—see revenues upward of $10 billion. Yet Creston’s U.K. revenue for the fiscal year ending in March 2006 was only about $87 million. Not only is Creston small, it’s not well-known on either side of the pond, despite such clients as General Motors, eBay, and Exxon Mobil.

For now, Creston’s only asset in America is Blamer’s reputation. He does, after all, have a much higher profile than the company he works for. “Blamer is a huge hitter to be sitting in Creston,” says David Wethey, chairman of Agency Assessments International, an ad industry consultancy headquartered in London. Blamer’s boss agrees. “I think that Steve’s profile undoubtedly is going to unlock doors,” Elgie says.

Blamer expects that five years down the road he will have “effectively cracked the U.S. market and provided a wonderful extension to our brother in the U.K. Hopefully Don will have filled in the Asian portion by then, and we’ll be a global company, a true global company.” Blamer will probably have a much nicer office as well.