LONDON—WPP today reported that revenue from its PR and public affairs firms, which include Burson-Marsteller, H+K Strategies and Ogilvy PR, grew 4.1% on a like-for-like basis during the third quarter of 2015.

The encouraging result saw PR revenues reach £225m for the quarter. For the year to date, PR and PA are up 2.2% to £687m.

In a statement, WPP CEO Sir Martin Sorrell said that PR and PA was the group's "strongest performing sector" after constant currency revenue and net sales growth of 5.4% and 5.2%, respectively during the quarter.

Sorrell also singled out Cohn & Wolfe and Group SJR for specific praise, along with the group's financial PR operations — which include Finsbury and Buchanan — in the UK.

"All regions, showed positive net sales growth in quarter three, with particularly strong growth in the United Kingdom, Asia Pacific and Latin America," said Sorell. "Quarter three and the first nine months both saw especially strong growth at Cohn & Wolfe and in social media content development in the USA at SJR, with financial public relations in the United Kingdom up strongly in the quarter."