Complex sentence: The company expanded, taking over a number of other shipping companies between 1951 and 1965, when it came under the ownership of the Ocean Steamship Company (Blue Funnel Line).
Split into simpler sentences: The company expanded, taking over a number of other shipping companies between 1951 and 1965. In 1965 the company came under the ownership of the Ocean Steamship Company (Blue Funnel Line).