There are three names in the history of popular music that represent the absolute pinnacle of the female voice. Whitney Houston. Mariah Carey. Celine Dion. Three voices so completely extraordinary so completely singular and so completely irreplaceable that most music professionals would never dare compare any living singer to any one of them let alone all three simultaneously. Then Leona Lewis walked onto the X Factor UK stage in 2006. A girl from London who had spent years trying to get a record deal the normal way and had been turned away every single time. Then she sang Over the Rainbow. And what came out of a young woman from London who had been told no so many times that she had finally decided to try something different was so completely extraordinary that three of the most experienced judges in music history began reaching for the only names they had that came close to describing what they were hearing. Whitney Houston. Mariah Carey. Celine Dion. Every single performance that fo...