Alastair Gornall, the chairman of Blue Rubicon, has resigned as executive chairman of political communications business Dods for personal reasons.
Gornall remains chairman of Blue Rubicon.
He took up the Dods role on 26 September, succeeding Kevin Hands, but according to the company has resigned "as a consequence of personal circumstances unforeseen when he first joined".
Dods has started a search for a new chairman and has appointed Andrew Wilson as interim chairman.
Wilson said: "The Board of Dods wishes to thank Alastair for all he has done in a short time to restructure the group and set a clear strategy. We respect his decision to step down at this time."