Greville-Bell was born in Sydney, Australia and educated at Blundell's School. On the outbreak of World War II, he enlisted and was commissioned into the Royal Engineers.
Greville-Bell married four times: to Diana Carnegie in 1945, Helen Scott-Duff in 1955, Ann Kennerley in 1972, the three marriages dissolved, and to Lauriance Rogier in 1996.
As a Sapper officer attached to 2nd SAS commanded by David Stirling he took part in Operation Speedwell against railway lines in northern Italy carrying German reinforcements and supplies to the front.
The troops landed by parachute but the officer commanding Greville-Bell's section dropped wide of the others and was not seen again. Greville-Bell took charge, despite having broken two ribs and damaged his back on landing. The section successfully attacked and cut the Bologna-Pistoia rail line and another south of Florence and destroyed a train.
Fourteen days after their drop, with their explosives and rations exhausted, they began 250-mile march south to join the advancing 8th Army. On the eighteenth day they reached the villa of the Marchese Roberti at Fiesole, overlooking Florence. A sister of the marchese was a friend of Greville-Bell's family and she sheltered and fed the party for a few days until contact could be made with the Italian partisans.
The armistice with Italy announced on 8 September meant the partisans proved less aggressive towards their former German Allies than Greville-Bell hoped but he stayed until he had gained enough strength to continue south. To mark 28 days in Italy, he and Sergeant Daniels went into Florence and drank some beer in a bar full of German soldiers. On the 30th day he, Daniels and two partisans blew a charge beneath a southbound train north of Incisa.
Seventy-three days after their drop, Greville-Bell led Daniels and Tomasso through the German lines to safety. He was awarded the DSO for his efforts.
Greville-Bell returned to the SAS after the war when the Malayan Scouts (SAS Regiment) were raised by Michael "Mad Mike" Calvert in 1950 during the Malayan Emergency.
After the war Greville-Bell travelled widely, including to Sri Lanka where his father had worked as a tea planter before the war. He wrote several screenplays, three of which were made into films:Perfect Friday, a British bank-heist film released in 1970, directed by Peter Hall and starring Ursula Andress, Stanley Baker, David Warner and T.P. McKenna.
The Strange Vengeance of Rosalie, released in 1972.
Theatre of Blood, a horror film released in 1973, directed by Douglas Hickox and starring Vincent Price and Diana Rigg.
Marked Personal, a TV series first shown in 1973 starring Stephanie Beacham and Carl Rigg.
The God King, a Sri Lankan historical film released in 1975, directed by Lester James Peries and starring Leigh Lawson and Oliver Tobias.
Sculpture had interested Greville-Bell since his schooldays, and he returned to it on a commercial basis in the late 1980s. His work featured nude female torsos, children's heads and birds.
His bronze of a wounded soldier being helped to safety by a comrade, mounted on Portland stone, stands in the SAS Garden of Remembrance.
Greville-Bell died in the United Kingdom.