Diet Coke redesigned its cans with the help of a tiny agency in the north of England

Diet Coke's new cans, introduced in January 2018

Diet Coke has redesigned its cans and introduced new flavors in an effort to appeal to a younger generation of drinkers and halt declining sales.

But rather than using a large international design agency to help it work out how to move the iconic fizzy drink into the future, it chose tiny U.K. company Kenyon Weston to revamp its packaging.

The business is a two-person agency based in Huddersfield in the north of England, run by Matthew Kenyon and Chris Weston. Coca-Cola's Vice-President of Design James Sommerville said it provided a new perspective on what the can would look like. Kenyon Weston worked with Coke's 26-year-old design lead Elyse Larouere on the sleeker cans, which feature a vertical band called the "high line."

Diet Coke's new cans, introduced in January 2018

"The marriage of the two, in theory, works well," Sommerville said in an article on Coca-Cola's website. "If a design project is too internally driven, we can end up talking to ourselves. And if we rely too much on external partners, things can go off the rails quickly. There is beauty in both knowledge and naiveté."

Sommerville chose Larouere to run the project because she is in Diet Coke's 20-something target audience — and is also a big fan of the drink. Like 44 million Americans, Larouere has a "side hustle," outside of work: She runs Shift, a company that holds week-long outdoor design camps.

The new flavors — ginger lime, feisty cherry, zesty blood orange and twisted mango — were tested with more than 10,000 people, with a focus on what millennials are eating and drinking. It took two years of focus groups and research to create the new flavors and a "mixology" session was held in Atlanta, where Diet Coke fans could create their own tastes.

Coca-Cola CEO: Broadening into new categories drives growth

Coca-Cola CEO James Quincey told CNBC's "Squawk on the Street" in November 2017 that the company was reinventing itself for a new generation, and called Diet Coke a work in progress. "I think you'll see more people moving into low-calorie products, less sweet products globally," he said.

The original Diet Coke flavor will remain the same, and the new lineup will be available in the U.S. in mid-January and in Canada in February. Other parts of the world are looking at future plans for the brand, the company said on its website.