Complex sentence: John Davies Gilbert and his son, Carew Davies Gilbert played a major role, as landowners, in the development of the town of Eastbourne and also developed Trelissick Garden in Feock, Cornwall.
Split into simpler sentences: John Davies Gilbert and their son, Carew Davies Gilbert played a major role, as landowners, in the development of the town of Eastbourne. They also developed Trelissick Garden in Feock, Cornwall.