WPP today reported that revenue grew 6.1 percent to £12.24 billion ($17.39 billion) for 2015. The ad/PR conglomerate also reported a 7.7 percent rise in earnings (before interest, taxes, and amortization) to £2 billion for the year, a new record for the company.

Q4 represented WPP's strongest quarter for the year. Like-for-like revenue was up 6.7 percent for the quarter (compared to third quarter growth of 4.6 percent), and like-for-like net sales grew 4.9 percent in Q4, putting organic sales growth for the year up 3.3 percent — ahead of forecasts — with organic revenue up 5.3 percent.

The world’s largest advertising group cited strong growth in North America, particularly in advertising and media investment management, as well as some of WPP's PR and public affairs properties, for the strong performance.

Total revenue at WPP's PR and public affairs operations grew 8.2 percent in the fourth quarter, with like-for-like net sales up 5.8 percent during the period ending Dec. 31. It was the strongest quarter of the year for WPP's PR and public affairs properties, whose revenues grew by a comparative 6.5 percent during 2015's third quarter.

WPP particularly cited PR growth in the U.K., Latin America and its Middle East and Africa regions, as well as strong performances by PR powerhouses Ogilvy Public Relations and Cohn & Wolfe. Burson-Marsteller and Hill+Knowlton Strategies, on the other hand, were “less buoyant” during the period, according to a press statement regarding the year’s preliminary results.

Despite the positive numbers, the marketing combine in a statement stressed cautious optimism for the year ahead.

“Despite this strong performance, the always on, Don Draperish general industry optimism seems misplaced,” the statement read. “To survive in the advertising and marketing services sector, you have to remain positive, indeed optimistic, seeing the glass half-full and industry and company reports generally continue, understandably, to reflect that attitude. However, general client behaviour does not reflect that state of mind, as tepid GDP growth, low or no inflation and consequent lack of pricing power encourage a focus on cutting costs to reach profit targets, rather than revenue growth.”

The company, which celebrates its 30th anniversary this year, reported that it expects performance in 2016 to be “very similar” to 2015, projecting net sales growth of over three percent and like-for-like revenue growth of "well over" three percent.