Sandoz will not be directly replaced. Instead, Gavin Gordon-Rogers and Gemma Butler, who were promoted to joint-creative directors in January, will take on his duties.
Sandoz would not comment on speculation he is planning a start-up. Nor would he comment when asked whether or not his future plans included working with Griffith again.
Jane McNeill, the managing director of Agency Republic, said: "We're sad to see Paddy and Andy go because we love them, but the graveyards are full of indispensable men. Our success has never been built on individuals."