RSA Insurance Group, an insurance company, has its registered office in Horsham. Sun Alliance merged with Royal Insurance in 1996 to form Royal & Sun Alliance Insurance Group, then renamed RSA Insurance Group in 2008. The company first came to the town in 1965 as Sun Alliance, becoming the town's biggest employer, at its peak, it employed 2,500 people, plus the specialised computer centre called Lennox Wood, sited in Southwater country park to which many of the original Horsham computer department staff were relocated. At its peak, the company occupied several smaller premises on the Carfax, Springfield House near St John the Evangelist Roman Catholic Church, the building that is now a study centre in Hurst Road, Parkside and the whole of the St Mark's complex, and print and security centres in industrial estates sprinkled around Horsham, plus Tricourt House closer to the Carfax and now occupied by a housing association. West Sussex County Council has partially occupied parkside after Royal Sun Alliance vacated the building.