For the UK’s retail marketers, there’s nothing more high-stakes than Christmas. And historically, there’s only one way to win it: with a big, glossy TV ad (and a huge media budget to boot). But with everyone in the same boat, getting cut-through is a challenge. So when Sainsbury’s asked us to help drive brand fame and love this Christmas, we looked to tangible brand experience.

The campaign proposition for Christmas was about giving it all you’ve got for the ones you love. So there was a clear opportunity to practise what we preach: to really go the extra mile for a community. We spotted an opportunity in Bude, Cornwall, where a Sainsbury’s trolley tunnel was racking up ratings as an attraction on TripAdvisor. It was a classic internet joke: trolley tunnel turned unlikely tourist destination. The perfect setting for a bold brand experience that would be uniquely ownable to Sainsburys.

The creative idea was simple. An unassuming trolley tunnel was becoming an unlikely tourist destination. We’d give it a Christmas makeover to make it truly worthy of a visit. In doing so, create a feel-good Christmas story that would entertain the tabloids, delight the internet, and win some real love for Sainsbury’s over the festive season. But with such a simple idea, execution was critical. The joke would only work if we approached it completely seriously and with absolute commitment to craft. That meant meticulous planning for the tunnel itself: 100,000 LED lights, tinsel, sound effects, an igloo selfie wall. This working trolley passage was going to be Britain’s spectacular Christmas light display. Secondly, and more critically: this had to feel homespun, grassroots, true to the original spirit of the tunnel’s TripAdvisor fanbase. We needed our store to be the star, not our marketing department.

We were all too aware of the worst case scenario outcome: brand ruins beloved internet joke. So although our ambitions were national, staging was crucial: this needed to be the feel-good local news story that accidentally got famous. Our PR strategy was therefore to start local, mobilising the community of Cornish & West Country media, many of whom had covered the original story of the tunnel’s TripAdvisor fanbase. We would hold off on a national push until enough momentum had generated from local media, selfie-taking visitors and social media fans, to really turn heads at national news desks. Absolutely key to the strategy was making Sainsbury’s part of the appealing comedy of the story. Against the spectacular light backdrop, our press shots focused on familiar brand assets: the baskets, trolleys, shopping bags, the purple fleeces and badges of staff colleagues. These would strengthen Sainsbury’s attribution, however the story was told.

A covert overnight operation revealed the new tunnel just in time for Bude’s big Christmas shopping weekend. Key community members fronted the reveal: Steve, the store manager, shot a lo-fi selfie film to share on his own channels. Our ambition was for the display to organically generate social noise over the weekend, fuelled by the tunnel’s own characterful perspectives on @BudeTunnel channels.

Our community-centred amplification approach paid off: local businesses, content creators and publishers were quick to build on the legend of the tunnel. Our media channels became fan t-shirts, cakes and naff knitted jumpers. We provided fodder for letterbox memes and culture mashups, gifs and selfies. All the while, Sainsbury’s stayed quiet, only making a splash a week later with a gentle wrap-up video. And it worked: with Sainsbury’s in the background, the stunt kept an authentic grassroots feel and honoured the humour of the original TripAdvisor story.

Bude couldn’t get enough of its tunnel. The internet lit up with selfies, driving visitors from all over the country and abroad. Within days it broke national papers, became #1 trending topic on Twitter and most watched on the BBC, topping a roll call of critical Brexit news pieces. It even trended on Fox News. Share of voice for Sainsbury’s on social skyrocketed 276%: extraordinary cut-through in a noisy Christmas marketing period.

On the ground, crowds were great news for Sainsbury’s cash tills, with 26% incremental sales uplift. But the real win was the depth of warm feeling and attachment for the Bude Tunnel. The online audience were unilaterally positive (>99%), and with hundreds petitioning to keep the tunnel up even longer. With the Bude Tunnel, Sainsbury’s set a precedent for a new kind of Christmas campaign: a magical real-world experience that got the whole nation smiling.