In 1958, he married Janet Cracknell (later Lady Marshall), a fellow officer on the Orient Steam liner named the Ostrava.

Marshall was hired by Lord King of Wartnaby in 1983 as CEO of British Airways (BA) and was instrumental in the reform of the company prior to its successful privatisation in 1987.

Following a highly publicised mercy mission to Iraq to fly home hostages of Saddam Hussein in 1991, King is reported to have told Marshall and his PR Director David Burnside to "do something about Branson"¹.

While helping to promote the government's Action 2000 campaign, which encouraged businesses to ensure that their computers recognised, interpreted, and processed the year 2000 date change, he was criticised for the contents of BA's own 1999 holiday brochures.

These warned travellers: "We will not cover claims arising from equipment or any computer program failing to recognise, interpret or process any date changes for example the year 2000."

From May 1996 to July 1998, Marshall was president of the Confederation of British Industry and chaired the CBI International Advisory Board.