With the help of Blackjack Promotions staff, shoppers will be offered samples of the Cadbury Dairy Milk chocolate and the opportunity to personalise packs of three chocolate bars using a selection of unique stickers, which can be applied to a gift sleeve.
Cadbury has created six different personalised stickers.
Three of them feature generic messages – Thankyou!, I [heart] you and Congrats! – while the other three have London-specific messages and images.
They include I [heart] London, a classic London routemaster bus modelled in chocolate and a Buckingham Palace-style sentry box and guardsman, again in chocolate.
The activation will be supported by bespoke 'Say it with Chocolate' gondola end display stands and Point-of-Sale material, plus, of course, space where the stickers and the sleeves can be displayed.
The promotion will run between April 15 and June 30 at London Stansted and between September 2 and November 17 at London Heathrow's Terminal 5.
Kay Walker, account manager, luxury, confectionery, WDFG & Airport Retailers at Blackjack Promotions, said: "This in-store promotion will give passengers the chance to add a unique personal touch to their chocolate."
Nicole Hatt, manager category marketing at Mondelez WTR, said: "From our global shopper research we learned that more than 60% of travellers think chocolate makes a good souvenir in a duty free store."