I have focused on here before on some of my favourite guitarists , bassists and drummers , perhaps thinking that singers get enough of the limelight as it is. But there is one particular group of singers that has intrigued me for a while. When I think of the great singing voices of the last sixty years or so, the really great ones I mean, there are some clusters across the years. There was a high volume of supreme singers coming out of the high-end jazz of the 1950s/60s (Ell