Complex sentence: In due course two AONBs, split along the county boundary, were designated, namely the East Hampshire AONB in 1962 and the Sussex Downs AONB in 1966, and these were later to form the basis of the South Downs National Park.
Split into simpler sentences: In due course two AONBs were designated, split along the county boundary, namely the East Hampshire AONB in 1962 and the Sussex Downs AONB in 1966. These were later to form the basis of the South Downs National Park.