Mark Irion has exited as CEO of Dutko Grayling, the U.S. public/government affairs arm of U.K.-based Grayling, a Huntsworth unit.

Irion told staffers that it was time to move on a little more than two years after the acquisition of the Dutko Worldwide lobbying firm by Grayling.

Huntsworth CEO Peter Gummer announced in October the formal creation of Dutko Grayling and expressed “every confidence that the U.S. team will make Grayling a more formidable presence in American government affairs, public affairs and public relations.”

Sally Withey, Huntsworth’s group COO, told O’Dwyer’s that Sara Parker heads up Grayling public relations in Washington now that Mark has left, alongside the rest of the senior management team at Dutko Grayling which comprises David Beightol (State and Local), Kim Bayliss and Arthur Silverman (Federal) and Ben Wallerstein (Consulting).

Gummer is chairman of Dutko Grayling.

Irion assumed the helm at Dutko in 2003. Before joining the shop, he was legislative assistant for energy and environmental issues for Sen. Alan Dixon (D–IL). In that spot, he helped craft the reauthorization of the Clean Air Act and other environmental legislation.

Betsy Hanlon, who began her career in the tax department at Price Waterhouse is COO of Dutko Grayling.

Meanwhile, Grayling today announced the World Water Council as a client for media and digital strategy.

Its teams in the U.K. and France handle the business.

The 6th World Water Forum is slated for Marseilles on March 12-17.