The most imaginative answer to this question is that several centuries ago, when what had started out as unfermented or lightly fermented green tea reached London after an 18-month sea voyage, it had all fermented and become black tea!
其中最富想像力的一種說法是：未經發酵或輕微發酵的綠茶，幾百年前經過十八個月以上的長途海運，在抵達倫敦時已經全部發酵，變成了紅茶！