People who engage with brands via social media spend between 20% and 40% more with the brand than other customers, according to global consultancy Bain & Company. Of course, that number is partly self-fulfilling, because shoppers who like and use a brand are the most likely to "like" it on Facebook, follow it on Twitter or collect images of its products on Pinterest.
Such is the power of the internet that the likes of Marks & Spencer and Argos, as well as Waitrose, have kept shoppers interested in their Christmas ads using social media competitions. John Lewis kicked off its festive campaign by creating a small forest on London's South Bank and an unbranded trailer on ITV to help publicise its Twitter hashtag #sleepingbear before the launch of its £1m Disney-style ad. It has racked up a heady 10m views online, more than 10 times the number of its nearest competitors.
Meanwhile, Sainsbury's this week said it was ditching celebrity chefs in favour of food bloggers including Jack Monroe, writer of A Girl Called Jack.
