Complex sentence: During the course of development of these areas the Clowes family kept tight control over the area to ensure that it remained "good class" and restricted the number of public houses that could be built and then only allowed beer to be sold and not spirits.
Split into simpler sentences: During the course of development of these areas the Clowes family kept tight control over the area to ensure that it remained "good class". They restricted the number of public houses that could be built and then only allowed beer to be sold and not spirits.