Complex sentence: At first it ran a single all-talk schedule across Sussex and Surrey, however in September 1997 two dedicated breakfast shows, one for Brighton and Hove on the old 95.3 frequency, and another for the remainder of Sussex, were introduced.
Split into simpler sentences: At first it ran a single all-talk schedule across Sussex and Surrey. However in September 1997 two dedicated breakfast shows, one for Brighton and Hove on the old 95.3 frequency, and another for the remainder of Sussex, were introduced.