Duncan Boyle has been replaced as chief executive of Royal & SunAlliance (R&SA) by Norwich Union sales and marketing director Bridget McIntyre.
R&SA said that Boyle had decided to retire after 32 years with the group.
Bridget McIntyre, 43 has worked at Norwich Union since 1993 and prior to that spent five years in finance roles at Volvo. She leaves NU with immediate effect and is due to start with R&SA in November.
Andy Haste, group chief executive of R&SA, said: "I am delighted to welcome Bridget to the Group. Her track record in the sector and proven ability to drive through change and deliver growth make her ideal to take the UK business to its next stage.
Duncan Boyle will remain with R&SA until the end of the year.