Previously, PHD UK reported through Pattison, who is an OMG board director, into OMG chairman and chief executive Daryl Simm in the US. It is understood that the change in reporting would have been made whether or not Pattison had decided to leave.
The move fuels rumours that Pattison resigned due to unease over the change in structure. Although he had global responsibilities for the PHD network, Pattison is based in PHD's London office and has been involved in the day-to-day running of the office since the departure of chairman Tess Alps in July.
PHD UK is now headed by Morag Blazey, who was appointed last week and who will now report to Gottlieb.