Murphy's departure comes just three months after the Harrison Troughton Wunderman co-founder Martin Troughton joined as the UK chairman of Red Cell Response in October.
Murphy joined the agency 18 months ago. During that time, he led its rebranding from Perspectives Red Cell and its move into premises in central London with its above-the-line sibling HHCL/Red Cell. He is also credited with hiring Gary Sharpen as the executive creative director.
Troughton, whose original brief was to develop the network's international capabilities, will add the running of the London agency to his current responsibilities.