LONDON--Omnicom Group has acquired a majority stake in UK public affairs agency Portland. 

Portland's senior management team, lead by founder and former Tony Blair aide Tim Allan, will retain a "significant stake" in the business, according to an Omnicom statement.

Portland has grown into one of the UK's leading lobbying firms during its 11-year history, and also operates smaller offices in Nairobi and New York.

“In a PR market that’s been hit hard by the recession, our growth and this significant deal buck market trends and that’s a testament to our outstanding team,” said Allan in a statement. “Looking back at where it all started 11 years ago with me and a laptop, it’s fantastic to be announcing a deal of this scale and to be planning the next chapter of Portland’s growth.

Reports suggest that Omnicom's investment values Portland at £20m, which would represent a surprisingly high multiple of its £1.35m profit in 2010. The firm earned revenues of £6.7m in the same year.

SI Partners advised Portland on the deal. It is understood the firm was previously in talks with Publicis Groupe and FTI Consulting.

Omnicom will now combine Portland with its existing g+ Europe public affairs network.

Peter Guilford, co-founder and executive chairman of g+ europe, said: “The combination of g+ europe in Brussels, Paris and Berlin and Portland in London and New York will be a force to be reckoned with in the international communications market. g+ europe and Portland have already worked successfully together on many projects and I’m confident this deeper partnership will achieve great things for our current and future clients.”