As a comparatively junior executive member of the P&O board, Marshall led the revolt that overturned the hostile assault on the shipping firm by the Bovis Construction company in 1972. Ford Geddes, P&O's chairman, had proposed that the company should take over Bovis Construction. With Frank Sanderson, Bovis's chairman and chief executive, set to become co- chairman of P&O, the proposal was in effect a reverse takeover. The board was split and much of the conflict between the two sides was conducted through the media.
Marshall bravely put his job and his future on the line. But he had a powerful ally - Kenneth Mackay, the third Earl of Inchcape, himself a non-executive of P&O and chairman of the family firm, Inchcape plc. An eventful City saga ensued, with Marshall writing to every shareholder in an attempt to galvanise support. The affair reached a climax at an extraordinary general meeting at the Chartered Insurance Institute Hall. Geddes's proposal was substantially voted down and he was forced to resign.
Inchcape then became chairman of P&O with Sandy Marshall his chief executive. The partnership lasted seven years, during which time Marshall was instrumental in the successful acquisition of Bovis, in 1974. But the partnership ended in tears. Marshall lost the confidence of his board and in 1979 he returned from a ship launch in Bergen to find no job, no secretary and virtually no desk.
He was saved partly by the greatest shipping magnate of the 20th century (and, indeed, the 21st so far): Maersk McKinney Moller, of Denmark, who gave him a seat on the Maersk UK board, where Marshall served for 15 years, from 1987 to 1993 as chairman. From that position he was elected President of the Chamber of Shipping in 1994 (a post he had been due to take up in 1980 but prevented by the knives of P&O and Overseas Containers Ltd).
At the same time Marshall embarked on a distinguished business career, becoming chairman of the engineering company Bestobell in time to fight off yet another takeover, as well as chairman of Commercial Union and vice-chairman of Boots.
Alexander Badenoch Marshall was born on New Year's Eve 1924, the son of a Dunfermline solicitor and First World War hero, and educated at Dunfermline High School, Croftinloan Preparatory School and Trinity College, Glenalmond. He went up to Worcester College, Oxford, in Trinity Term 1942; he wanted to fit in four terms at Oxford before joining the Navy. His naval service - as midshipman and sub-lieutenant - was almost entirely in the destroyer Oribi, supporting the Normandy landings and escorting troopships in the Atlantic and merchant ships on the merciless Russian convoys to Murmansk. He returned to Worcester in Michaelmas 1946, reading Political Science and gaining a war degree.
He joined the firm of MacKinnon MacKenzie, managing agents of the British India Steam Navigation Company and agents for P&O, in Calcutta in 1947. After 13 years in India he was given the opportunity to start from scratch a new tanker company within P&O, Trident Tankers. Its success led to his joining the P&O board in 1968 as its first executive director.
The story of the Bovis/P&O "takeover" is well told in Marshall's autobiography, Taking the Adventure (2000), and the "ABM Archives" are now deposited in the National Maritime Museum, where they will make fascinating research for any shipping historian. Marshall's achievements led to an offer of appointment as CBE in 1993. Anticipating a knighthood, he unwisely turned it down.
In the same year, cancer was diagnosed. For 11 years Marshall endured marvellous treatment from the Royal Marsden. He was determined to make his 80th on 31 December, which he did, though sadly he was not well enough to attend the dinner party downstairs.
Alexander Badenoch Marshall, shipping director and businessman: born Dunfermline, Fife 31 December 1924; general manager, British India Steam Navigation 1959-62; managing director, Trident Tankers 1962-68; director, Peninsular and Oriental Steam Navigation 1968-79, managing director 1972- 79; vice-chairman, Maersk 1983-87, chairman 1987-93; chairman, Bestobell 1979-85; chairman, Commercial Union Assurance 1983-90; vice-chairman, Boots 1985-91; President, Chamber of Shipping of UK 1994-95; married 1961 Mona Kirk (two sons, one daughter); died Sutton, Surrey 12 January 2005.