For many of us coffee offers a much-needed boost, but we may be getting much more - or less - caffeine than we bargained for at popular High Street coffee shops. Consumer group Which? measured the caffeine in drinks at five big chains and says it found "huge differences".
An espresso at Pret for example had six times as much as one in Starbucks's. A medium cappuccino at Costa Coffee has 325mg of caffeine - far more than rival drinks and equal to four cups of tea.