Complex sentence: He then joined some of his father's businesses, becoming a director of-and from 1940 to 1947 chairman of-Imperial Chemical Industries and he was also a director of the Mond Nickel Company and Barclays Bank.
Split into simpler sentences: He then joined some of his father's businesses, becoming a director of Imperial Chemical Industries and serving as chairman from 1940 to 1947. He was also a director of the Mond Nickel Company and Barclays Bank.