In a speech this week, Prince Charles suggested that people remember not to fill their kettles too full. Here he explains why:  It seems to me that most people instinctively understand that to make a cup of tea it is not necessary to boil an entire kettle! And I, for one, simply cannot sit here and do nothing while, all around the world, whole kettles are boiled, regardless of the tragic consequences.  Do we need kettles at all? I happen to think their benefits are limited. In my quest to address the challenge of making tea without using a kettle, I sought to create a new example of sensitive, cauldron-based boiling that reflected local tradition and character. Despite a few early hiccups (very few supposedly advanced vacuum flasks are capable of keeping water at boiling point, even on the relatively short helicopter flight to Scotland), I am pleased to report that we are beginning to make a difference. Since a promising experiment with heated stones led to one or two minor injuries, all our tea at Highgrove has been made using energy from an open fire, kept  burning for the purpose, or inside a seasonal compost-warmer.  I happen to think that when consumers appreciate the difference between water that has been prepared without a thought, in a few seconds, and liquid from a pot, like ours at Highgrove, which has taken hours, perhaps days, of careful tending to reach boiling point, they too will reject kettles as not just unnecessary, but unacceptably black.