As a sapper officer attached to the 2nd Special Air Service (SAS) commanded by Bill Stirling, Greville-Bell took part in Operation Speedwell against railway lines in northern Italy carrying German reinforcements and supplies to the front in September 1943.
Fourteen days after the drop, with their explosives and rations exhausted, they began 250-mile march south to join the advancing Eighth Army.
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 1943 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.
His bronze of a wounded soldier being helped to safety by a comrade, mounted on Portland stone, stands in the SAS Garden of Remembrance.