If you move to England from the US will your accent eventually change?

I was watching the show house hunters international and the woman was American and from one of the deep south south states, I think either Alabama or Mississippi. Said she had been living in England for 3 years, and she had a full English accent(kind of think she was faking it).. I would think the only way your accent would change is if you were young and went to school there....So is there a possibility an American(southern at that) will pick up an English accent or was the women full of SH*& and more than likely faking it?