The arms were designed by Mr C W Scott-Giles, Fitzalan Pursuivant of Arms Extraordinary. The designer took as his natural starting point the original arms of Lucy Cavendish herself, and these appear in the base of the shield, the silver stag's head on black for Cavendish (the family of the Dukes of Devonshire) and the scallop shell for Lyttelton (her maiden name). In the upper part we have a waterlily as an emblem of a new and growing College. The waterlily is set against the blue and white wavy lines representing the river Cam, and the stem grows out of the rich black Fenland soil below. The arched curve across the shield provides a reference to the arch of the bridge over the river, as seen in the arms of the City of Cambridge.

The crest displays the pearly nautilus shell, another very personal emblem in the history of the College. The nautilus shell is unusual if not unique in heraldry, although it was used as a personal emblem in the sixteenth and seventeenth centuries. It can also symbolise the spirit of adventure and scientific exploration, as a creature 'voyaging through strange seas of thoughts alone'. In the Lucy Cavendish crest the nautilus is shown supported by the ocean, the wavy bars of the circle. The little gold stars are symbols of light and refer to the name of Lucy.