The agency, which won the account after a competitive pitch, has been briefed to raise awareness of the issues surrounding supermarket unit pricing. Activity will also include an experiential strand targeting consumers, retailers and the government to raise awareness of confusing in-store pricing.

Which? head of advocacy Louise Hanson said: "Inconsistent unit pricing in UK supermarkets is a real issue for consumers. We are campaigning for consistent, visible and user-friendly unit pricing that takes away the confusion and makes it easier for people to compare prices and work out which product offers the best value for money.

"We liked Citizen's campaigning experience and approach, which combines rational insight into the way audiences behave with emotional, engaging stories and hooks to create action."

Citizen MD Mandy Sharp said: "We're thrilled to be working with iconic consumer brand, Which?. The key to this campaign is to generate people-powered conversations which then provoke action. We can't wait to get to work."