At Chemistry, Harle replaces Mike Cavers, who left in August to join The Marketing Store. Cavers was credited with raising the agency's profile and restructuring its creative output to incorporate digital, direct and promotional marketing.
Harle will be responsible for overseeing Chemistry's creative product across all clients including Orange, Emirates and TfL, as well as building the agency's integrated credentials and attracting new talent.
He joins after a period away from the industry after exiting Targetbase Claydon Heeley in April 2009 after the merger of Claydon Heeley with Targetbase and the arrival of Chris Martin as integrated creative director.
Harle worked at Claydon Heeley for nine years. He joined, along with his former creative partner Dave Woods, in 2001 from TBWA. The pair progressed to executive creative directors of Claydon Heeley, at one point taking over the creative output of Agency Republic before Woods left to join RMG in 2007.
During Harle's time at Claydon Heeley, the agency was named Campaign's Direct Agency of the Year in 2004, producing memorable campaigns for clients including The Guardian and Mercedes.
Harle said: "The agency has the ambition, the clients and most importantly the people to create rich, exciting ideas."