This year's Christmas campaign from Sainsbury's swings away from the blockbuster style and animated cuteness of its last couple of years, as the U.K. supermarket takes a different approach from most of its rival retailers and opts for a catchy original song about Christmas, featuring real customers and employees.

The ad, by Wieden + Kennedy London, continues its "Living Well" campaign with its distinctive black- and-white film dotted with splashes of color-- in this case, both the Sainsbury's orange logo and a bright green Brussels sprout which bounces along the tops of the lyrics, karaoke style.

The song "Every Bit of Christmas" was composed by musician and comedian Ben Smith, aka "Doc Brown." A collection of street-cast real people, as well as Sainsbury's employees, sent in audition tapes to be cast as the ad's singers and stars. There's also a rapping child, a singing dog and a couple of celebrities (Kermit the frog and actor Ricky Tomlinson from "The Royle Family"). The campaign was shot on location in London, Cardiff, Manchester and Glasgow with a cast of 200. Despite the distinctly British feel, it was directed by We Are From L.A, the French duo behind Pharrell Williams' "Happy" music video, via Iconoclast.

A karaoke version will be available for people to sing themselves, while 25 different versions of the ad will air over the holiday period. Unlike rivals such as Marks & Spencer, Aldi and John Lewis, the Sainsbury's ad will have no themed merchandise tie-in. According to Laura Boothby, head of broadcast communication, while these have worked well for the brand in the past, this year Sainsbury's wanted to concentrate on food, "as that's what we sell most of at Christmas."

Boothby says the retailer has opted to stick with its black-and-white "Living Well" campaign for Christmas rther than go for a "Christmas special" as its research so far suggests the campaign "cuts through" and is distinctive, with customers responding well to its diversity and behaviour they could recognize, like texting the family to find out what's for dinner.

Recent Christmas ads, by its previous agency AMV BBDO, featured children's book character Mog and last year, an original animation with a song sung by James Corden. In 2014, the retailer won plaudits for its recreation of the Christmas truce between soldiers in the First World War. W+K took over the account last January.