The mighty Tesco are running trials of free in-store Wi-fi. Having not been in one of the four stores testing this, I’m making my best guess, but it would not surprise me one bit if you need to have a Tesco Clubcard to log on, your browsing habits will be collated, and the next batch of Clubcard offers will be influenced by the sites you looked at during your shopping. Which are more than likely going to be Amazon, Asda and Sainsburys.