The company, which offers both market research and market access services to the pharmaceutical and medical device industries, was founded in 1995 by CEO Wayne Phillips (pictured), who will continue to lead the company but will report in to McCann Health CEO John Cahill.

Phillips said the acquisition “provides us with the resources to create an exciting and fulfilling future through the continued development and further internationalisation of the business”.

Double Helix was one of the ten fastest-growing research agencies in our last annual industry review, with revenue up 34% to £16.4m in 2010.

Phillips told us at the time: “We’ve never had any acquisitions or borrowings. I basically started the business with £5,000 and everything since has been down to organic growth.

“We retain a great amount of business but we also added some very good new clients in 2010. Expansion has come from all operations: market research and market access in the UK and the US, and it’s continuing this year. Emerging markets has been an area where we’ve grown. We’re getting more and more business in China, Brazil etc. But most of our business comes from operations in the US, UK and Europe.”

Double Helix has offices in London, New York, Philadelphia and Singapore.

Terms of the deal were not officially disclosed, but Sky News city editor Mark Kleinman blogged that sources had told him the acquisition price was £35m, potentially rising to £50m depending on performance.

McCann’s Cahill said: “For some time, we have been working to elevate all of our offerings by several orders of magnitude. With Double Hellix, we now have the basis for the best market research and market access offerings in the business.”