To be consistent in his use of English and, more importantly, to be understood , the non-native speaker needs to know which words have distinct meanings and pronunciations depending on whether they are used by a Briton or an American. This is necessary not only for sake of communication, but also to avoid embarrassment. For example, if a Londoner tells a resident of New York that she has left her child's dummy in the pram and its nappy in the boot, she will merely be greeted with a look of bewilderment. If the New Yorker then tells the London woman that she has nice pants, he may well wonder why she doesn't seem to take his remark as a compliment.