Mark Cadman is joining JWT as its managing director, ending the speculation surrounding his future since he was denied the chance to take charge of Lowe London.
The agency named Garry Lace as its chief executive at the beginning of the year, a role Cadman is thought to previously have been offered in writing. Cadman is understood to have received compensation from Lowe.
His appointment will be seen as a move by JWT to enhance its chances of capturing the £47 million Sainsbury's account, currently held by Abbott Mead Vickers BBDO.
Cadman was the senior suit on the rival Tesco account at Lowe, where he was the managing director. He and Russ Lidstone, the ex-Lowe planning chief signed by JWT in January, were among the key individuals who kept Tesco locked in despite Lowe's recent upheavals.
JWT is also challenging Lowe strongly on Nestle, having recently captured the foods giant's Quality Street, Double Cream and Milkybar brand assignments.
The two networks are also battling it out for Persil's global account.
Cadman's arrival at JWT coincides with the promotion of Lindsey Clay from head of account management to deputy managing director.
The managing director's role at JWT has been vacant since last May, when Ros King relocated to New York to become the global business director on Kraft Foods.
Cadman, 40, who worked at JWT for two years from 1995, is believed to have been sounded out about a return last year. He opted to remain at Lowe, in the belief that he was in line to succeed Matthew Bull as the agency's chief executive.
Cadman joined Ammirati Puris Lintas in 1997 to run Rover, becoming its client services director the following year. After the merger of APL and Lowe Howard-Spink, he was appointed as the client services director of the merged agency.
Simon Bolton, JWT's chief executive, said: "Mark fits perfectly with JWT's new point of view."
Cadman said: "I relish the challenge of working on big business and the chance to help develop big creative ideas. Right now there is no better agency to join in this regard than JWT."