In 1949, during the Yangtze Incident, he received the PDSA's Dickin Medal after surviving injuries from an artillery shell, raising morale, and killing off a rat infestation during his service.

[1] Simon was found wandering the dockyards of Hong Kong in March 1948 by 17-year-old ordinary seaman George Hickinbottom, a member of the crew of the British frigate HMS Amethyst stationed in the city in the late 1940s.

Hickinbottom smuggled the cat aboard ship, and Simon soon ingratiated himself with the crew and officers, particularly because he was adept at catching and killing rats on the lower decks.

Whilst in quarantine, Simon contracted a virus and, despite the attentions of medical staff and thousands of well-wishers, died on 28 November 1949 from a complication of the viral infection caused by his war wounds.

The following citation accompanied the Amethyst campaign ribbon: [For] distinguished and meritorious service... single-handedly and unarmed stalk down and destroy "Mao Tse-tung" a rat guilty of raiding food supplies which were critically short.