Complex sentence: The main industry in the village was a coal mine owned by J. Lovell & Sons from 1835 to 1929, which was part of the Somerset coalfield, and also had a large flour mill, part of which was converted into flats.
Split into simpler sentences: The main industry in the village was a coal mine owned by J. Lovell & Sons from 1835 to 1929, which was part of the Somerset coalfield. There was also a large flour mill, part of which was converted into flats.