Oliver Dowden makes the switch to public affairs as the Tories continue to improve their standing in the polls.
He will join the agency in January as managing consultant, reporting to public affairs MD Tim Fallon.
Dowden has spent the past three years working closely with Conservative leader David Cameron. Before this, he was as an account director at lobbying firm LLM.
Earlier this year, Tory campaigns director George Bridges moved to London corporate PR shop Quiller (PRWeek, 21 September).