Sailing alone, his motor tanker, the San Emiliano, was torpedoed and sunk by U.155 in the central Atlantic, south east of Trinidad.

He rowed the lifeboat, the only one to survive the sinking, for two hours despite his hands being so badly burned they had to be cut away from the oars as his flesh had stuck to them.

Lying at the bottom of the boat, as they waited for rescue, he sang to keep up the spirits of the other men.

[3] The citation ended thus "By his supreme effort, undertaken without thought of self and in spite of terrible agony, Apprentice Clarke ensured the safety of his comrades in the boat.

His great heroism and selfless devotion were in keeping with the highest traditions of the Merchant Navy."