On my daily trundle down my local high street, I’ve been marking the changes as shopfitters swoop in with pink or white or glittery shop furniture. Almost every new shop in this corner of north London seems to be a teen- and family-friendly cafe selling bubble tea, sweet fluffy pancakes, ice-creams or desserts with names such as “choco coma”. Sugar is cheap, so the shopkeepers need to sell a lot of treats to make it pay. Fortunately for their business model, but unfortunately for the nation’s health, Britain consumes twice as much sugar as it should. I tut inwardly at…