Activity starring Seb White comes as the retailer seeks to promote its kidswear within its Christmas advertising and marks a distinct departure from last year's campaign featuring the stars of 'The X Factor'.
Seb was chosen after his mother Caroline posted on the brand's Facebook page, asking M&S to consider using her son in advertising because youngsters with Down's Syndrome were not represented in modelling campaigns.
Steve Sharp, executive director of marketing at M&S, said: "Our initial involvement with Seb was due to the overwhelming response to Caroline's post on our Facebook page.
"However, he won his place in our TV ad thanks to the natural charm and magical personality he showed on set at our magazine shoot. All the kids had great fun filming the ad and Seb really was one of the gang – which is exactly how it should be."
The M&S Christmas campaign will feature the strapline, "The greatest hits this Christmas" and was inspired by the Christmas compilation album format.
Five backing tracks will feature on the ad, including a never-before released Rod Stewart cover of 'Have Yourself a Merry Little Christmas'.
Creative by Rainey Kelly Campbell Roalfe/Y&R is shot in the style of a music video that moves through five product scenes, including "cosy knitwear" and "stylish party outfits".
The products will be showcased featuring models of different shapes, sizes and ages, as part of the retailer's policy of giving its customers "more products, more diversity and an injection of style and fun".
M&S is focusing on its clothes offering as it prepares to announce financial results tomorrow (6 November) that are expected to show a 5% decline in like-for-like general merchandise sales for the six months to 30 September.
Television activity features a final scene where kids take centre stage by dancing to Kool & the Gang’s 'Celebration' track while wearing M&S knitwear.
Other scenes in the ad feature women playing in the snow to the Rod Stewart track; a scene set in the office accompanied by Jean Knight's 'Mr Big Stuff' track; girls taking to the dancefloor to party to the INXS song 'I Need You Tonight', and a sleepwear scene set to' Lady Marmalade'.
The ad will debut on Wednesday (7 November) on ITV during 'Coronation Street' and will be available to view earlier on the M&S website.Follow @mattchapmanuk