Patrick Snowball, the head of Norwich Union, has left the insurer to join Towergate after a disagreement with incoming Aviva chief executive Andrew Moss.
Snowball is understood to have resigned after Moss unveiled his plans for the future of the insurance group.
According to reports, these include splitting Snowball's role and removing his reponsibility for expanding Aviva's outsourcing operations in India.
Snowball, who is responsible for Aviva's UK life and general insurance businesses, was beaten to the top job at Aviva by Moss after Andrew Harvey announced his retirement this year.
Snowball will leave the group at the end of June 2007 to take up the role of deputy chairman at Towergate Partnership.
Moss has also announced a major overhaul of the group executive team, which will see Philip Scott, currently executive director for Aviva's operations outside Europe, will become finance director.
Tom Godlasky, currently chief executive, Aviva USA, will become chief executive, North America, and will lead Aviva's operations in the USA and Canada.
Simon Machell, currently chief executive, Norwich Union General Insurance, will become chief executive, Asia Pacific, and will lead Aviva's Asian and Australian businesses.
Igal Mayer, currently chief executive, Aviva Canada, will become chief executive, Norwich Union General Insurance.
