Shoppers across the UK passing their local Primark were puzzled this weekend as they spotted Greggs steak bakes and vegan sausage rolls discreetly tucked into mannequins’ handbags and pockets in window displays. Their curiosity was piqued further on Primark’s social media accounts, which displayed a receipt showing items from the Gregg’s menu with a curious emoji. The secret has now been revealed as the two popular high street retailers announced a partnership on their social media channels in a carefully curated PR moment, announcing the launch of a new fashion line on 19 February and the opening of Tasty by Greggs, a new cafe in Birmingham’s Primark branch said to be the “world’s most Instagrammable Greggs”, a week before on 12 February. The launch video promised: “One does tidy food, one does tidy fashion. Together we’re unstoppable.” The errant baked goods prompted a lot of speculation about the collaboration on social media at the weekend. One commenter, whose tweet received thousands of likes, said: “Shoutout to whichever stone cold legend at Newcastle Primark has accidentally left a load of Greggs in the window display.” The 130-seater cafe will open in Primark’s largest store selling Gregg’s signature dishes including sausage rolls, bakes, pizza, desserts and coffee. It promises “the ultimate Greggs experience”, replete with tables decorated to look like doughnuts and a doughnut swing where the brand hopes customers will take photos to post on Instagram. Greggs has yet to reveal the clothing line, and whether it will feature prints of its iconic baked goods, however one PR image shows a simple hoodie featuring the Greggs logo. The limited-edition range of 11 pieces will be available in 60 stores. Raymond Reynolds, the Greggs business development director, said that customers had “continually asked” for Greggs branded clothing. “Fans can quite literally show their love for Greggs on their sleeves,” he said. Greggs and Primark will open a pop-up boutique in Soho between 17 and 18 February to “offer eager fashionistas the chance to get their hands on some of the new collection before the rest of the nation”, with two pieces available for free to those who manage to secure a slot when bookings open on 10 February. Tim Kelly, the director of new business development at Primark, said the retailer was looking to team with brands “we know [our customers] love” on clothing ranges and in-store experiences. Collaborations are increasingly popular among brands to enable them to reach two sets of customers at once. One of the most iconic brand partnerships is between Nike and Apple, which was formed in 2006 and includes Apple Watch Nike, a collaboration that brings together technology and fitness.