Act I of "Song and Dance" (which is a slightly reduced version of "Tell Me On A Sunday") tells the story of a British girl in New York and LA, adjusting to life in America, writing letters back to the UK, falling in and out of love etc ..... The role of Emma is written to be played as a Brit, and when I saw Bernadette Peters play it back in the mid-80s, she spoke and sang with a British accent. Without massive revisions to the text (which Webber and Don Black thus far have shown no interest in doing), it wouldn't make any sense for Emma to be played as anything other than British.
"What a story........ everything but the bloodhounds snappin' at her rear end." -- Birdie
[http://margochanning.broadwayworld.com/]
"The Devil Be Hittin' Me" -- Whitney