Sun Alliance Group plc was a large insurance business with its main offices in the City of London and later Horsham. It was created in 1959 by the merger of Sun Insurance, founded in 1710, and Alliance Assurance founded in 1824. In 1996 Sun Alliance merged with Royal Insurance to form the Royal & Sun Alliance Insurance Group.

Horsham is a market town on the upper reaches of the River Arun on the fringe of the Weald in West Sussex, England. The town is 31 miles (50 km) south south-west of London, 18.5 miles (30 km) north-west of Brighton and 26 miles (42 km) north-east of the county town of Chichester. Nearby towns include Crawley to the north-east and Haywards Heath and Burgess Hill to the south-east. It is the administrative centre of the Horsham district.