Morna McLelland, who has been with Stripe since 2008, becomes managing director with responsibility for day-to-day running of the business. Simpson will focus on providing senior client counsel, business strategy and exploring expansion options.
Two further additions to the board are Jenny Ingram and Stephanie Robertson, together with the recent appointment of digital director Darcie Tanner. At management level, Simon Ebbett and Stuart Martin have both been promoted to senior account director.
The board will report directly to Cello Signal, a division of Cello, the healthcare and consumer marketing group.
Edinburgh-based Stripe was founded in 2006. Its key clients include John Lewis, Magners, AG Barr (owner of Irn Bru and water brand Strathmore), ScottishPower, the Scottish Government and windows and skylights supplier Velux.