The agency has signed up Victoria Roberts, a former aide to Commons speaker John Bercow, as a senior consultant.
Roberts spent three years as a researcher for Bercow from 2004 to 2007 before going on to train as a barrister. She is also deputy chair of the Tory Reform Group, which promotes one-nation Conservatism.
Game Changer was set up earlier this year by Labour stalwarts David Prescott and Alex Hilton. Prescott is a former head of media at Geronimo Communications and son of the former deputy prime minister. Hilton is co-founder of the LabourHome website.