A box of paper clips. A sink plug. A bag of gravel. Those were among the creative assets that won the Grand Prix in the promo and activation category at the Cannes Lions International Festival of Creativity. The winning work: The "Sorry, I Spent It On Myself" Collection for U.K. retailer Harvey Nichols, created by Adam & Eve/DDB.

What it is: The luxury retailer launched a holiday promotion that cheekily promoted selfishness by selling a gift collection of inexpensive items including rubber bands, cheap pens, canned food and the aforementioned paper clips, sink plugs and bags of gravel. The idea: Spend little money on other people's gifts and you'll have more to spend on yourself.

Why it won: A combination of smart strategy and strong execution made it the victor, according to the jury. It also worked. "Brick-and-mortar sales are on a decline year over year," said juror Will Clarke, executive creative director at The Integer Group. "And for Harvey Nichols to come in and have one of the best holiday campaigns really spoke to the connection with the shopper and customer and the level of creativity. There are a million ways to solve a problem these days and they solved it with retail promotion."

The jury: The 28-member jury was chaired by Susan Credle, chief creative officer of Leo Burnett U.S.A. One of the reasons it was drawn to the Harvey Nichols work was its commercial nature. "Because of social media we've been able to do these mass pieces that the whole world gets involved in, and we tend to not look at pieces like Harvey Nichols, which is targeted to a retail moment in a year," she said. "And that's a lot of what we have to do in marketing and advertising: move product in a certain time of year."

Controversy or clear winner: The other campaign in contention for the Grand Prix was "We Are All Monkeys," a Brazilian anti-racism campaign with soccer star Neymar, created by Loducca, São Paulo. The jury debated whether that was a charity campaign (and thus not eligible to win the Grand Prix) but in the end decided it could count toward the Grand Prix. "It got more and more conversation as we went," said Ms. Credle. Also surfacing in the Grand Prix discussions: "The Speaking Exchange," a campaign out of FCB Brasil, São Paulo, for CNA's English language courses, which paired English students with residents of U.S. retirement homes.

Total number of Lions awarded: The jury awarded 20 gold Lions, 29 silvers and 44 bronzes. The U.S. was shut out of gold Lions.

For more Cannes work highlights, tune into Creativity's "The Best of Cannes."