Complex sentence: Shelbourne started his City career when he gave up the Bar to take up a partnership at NM Rothschild, and he, with Jacob Rothschild and Rodney Leach, formed a team in the late 1960s.
Split into simpler sentences: Shelbourne started his City of London career when he gave up the Bar to take up a partnership at NM Rothschild. With Jacob Rothschild and Rodney Leach, he formed a team in the late 1960s.