The WPP-owned shop had already received a Grand Prix for "life paint" on Monday in the Promotion and Activation category, as well as a silver Lion.
The campaign, which aims to promote cycling safety and draw attention to Volvo’s XC90 marque, saw Grey team up with Swedish startup company Albedo100 to release a spray paint that makes surfaces glow in the glare of headlights.
The work included an online film and posters treated with Life Paint that reveal their message when hit by a camera’s flash.
"Life paint" also won a bronze Lion and was one of 14 awards won by UK agencies in the Design category tonight.
Eight silver Design Lions were awarded to UK agencies, including DesignStudio’s rebranding work for AirBNB, which also won a bronze.
Other silver wins were: Mill+London for its D&AD title sequence; 4creative’s Film4 idents; Leo Burnett London’s "suffocation" campaign for Karma Nirvana; Google Creative Lab’s "Inside Abbey Road" work for Abbey Road Studios; AKQA London’s "house of mamba" work for Nike, and Ogilvy & Mather London’s "it happens here" ad for 28 Too Many.
Five bronze Lions went to the UK in total: Grey London’s "life paint"; DesignStudio’s AirBNB rebrand: AKQA London and AKQA Shanghai’s "house of mamba" for Nike; Here Design’s work for Adidas’s Original Neighbourhood Stories, and Fitch for its "formation" work for Adidas during football's World Cup 2014.
Grey London's "life paint" was also shortlisted for the Product Design Lions – the only UK agency to be nominated this year – but did not win an award tonight.
The Grand Prix in that category went to Geometry Global Dubai for "the lucky iron fish project".