Complex sentence: After the war, he resumed his career with HSBC and, in 1953, succeeded Sir Arthur Morse as Chief Manager of HSBC in 1953 where he was instrumental in the considerable post-war expansion of the bank.
Split into simpler sentences: After the war, he resumed his career with HSBC and, in 1953, succeeded Sir Arthur Morse as Chief Manager of HSBC. He was instrumental in the considerable post-war expansion of the bank.