Buchanan will join the agency in the coming months, reporting directly to Publicis Group UK’s chairman and chief executive Nigel Jones.
She has worked at The Red Brick Road since 2006, running all aspects of the agency’s Tesco account.
Previously, Buchanan was at DDB UK, where she had worked her way up to head of account management.
Simpson had been chief executive of the agency since 2007 but is leaving as part of a restructure that follows Publicis Groupe’s acquisition of the direct and digital specialist Chemistry Communications, which has now officially gone through.
Chemistry will be merged with Publicis Dialog to create the UK’s second largest direct marketing agency. The new agency, which will assume the Chemistry name, will consist of more than 250 staff and have revenues approaching £30 million. It will be led by Chemistry chief executive Joe Garton, managing director Diane Charlton and Dialog’s chief executive Mike Welsh.
Publicis Modem and Publicis Blueprint will sit alongside Publicis London and Chemistry in a four agency UK group.