If you listen to very early Beatles, for instance "Love Me Do", they most definitely come from Liverpool. Within a few records it was much less clear, and there was indeed an americanness about them but the time of, say, "I wanna hold your hand". Why? I think because they had realised that they really were going tobe able to sell a lot of records, and they could work out that the record buying public in America was much larger than in Liverpool, or indeed the whole of the UK.   

Now putting on a West Indian accent, that had rather different overtones. People of West Indian origin have suffered appalling racism in the UK, and therefore I think that Pete Waterman (whom I have very little time for on any subject, especially railways), was right to pull the contestant up. Maybe he should have pulled Sting up too, but thats another issue.