Complex sentence: Eventually the Midland (head office in Derby) owned a large network of railway lines centred on the East Midlands, and the main lines connecting the East Midlands to Birmingham and Bristol, and another to Manchester.
Split into simpler sentences: Eventually the Midland owned a large network of railway lines centred on the East Midlands, and its head office was in Derby. The company also owned the main lines connecting the East Midlands to Birmingham and Bristol, and another to Manchester.