Complex sentence: Dolphin became the Managing Director of the Corgi Motorcycle Co Ltd. in 1946 and also set up Dolphin Industrial Developments Ltd, and Hydraulic Developments Ltd, which he ran until 1950 when he became Chief Engineer at the Atomic Weapons Research Establishment from 1951 to 1957.
Split into simpler sentences: Dolphin became the Managing Director of the Corgi Motorcycle Co Ltd. in 1946 and also set up Dolphin Industrial Developments Ltd, and Hydraulic Developments Ltd, which he ran until 1950. He became Chief Engineer at the Atomic Weapons Research Establishment from 1951 to 1957.