WASHINGTON, DC--Mark Irion has abruptly departed Dutko, four months after the public affairs firm was rebranded as Dutko Grayling.

Irion was charged with leading Dutko Grayling's public relations and public affairs unit, in line with the UK network's plans to build a stronger global public affairs offering. Grayling acquired lobbying firm Dutko, which Irion had led as CEO since 2003, in late 2009.

In an internal memo announcing his departure, Irion apologised to colleagues for the "abruptness" of the news. "So now two years into the acquisition it's time for me to get started on some long brewing ambitions," he adds.

Irion headed Dutko's energy and environment division, before being named president of the firm in 1996. He helped build the firm into one of DC's top five lobbying shops, with a particular focus on integrating advocacy, government relations and public affairs.

Before joining Dutko, Irion worked as a legislative assistant and Senate aide, focusing on environmental and energy issues.

Dutko's lobbying income has declined since 2007. In 2011, its earnings from lobbying dropped by around a third compared to 2010. Huntsworth CEO Lord Chadlington, whose company owns Grayling, told the Hill that the firm's repositioning would help reverse this decline. 

"We all worked too hard from where we began to become a top 10 firm, and then a top five firm for six years running to not keep building," adds Dutko in the memo. "Whatever challenges lay in front to reclaim that position are nothing compared to what it took us to get there."