Technology giant IBM has clinched a ten-year outsourcing deal with Royal & SunAlliance (R&SA).
As part of the deal, 285 of R&SA's IT employees, from a number of sites including Horsham, Liverpool, Bristol and Halifax will transfer to IBM.
No redundancies are planned as a result of the move.
R&SA's average annual spend on IT is around £50m and it is anticipated that 10% savings will be achieved over the course of the ten-year agreement.
The deal, for an undisclosed sum, covers the management and development of R&SA's IT infrastructure in the UK, which includes mainframe, mid range and desktop computing services.
R&SA chief executive Paul Spencer said: "Our partnership with IBM will ensure we are able to fully harness the potential of the internet and other emerging technologies."