Today, Leona Lewis's long reign at No 1 with 'Bleeding Love' will probably end. The upsetter? A cover version of Louis Armstrong's 'What a Wonderful World', sung by Katie Melua and Eva Cassidy, and benefiting the Red Cross. It's only available through Tesco.

Cassidy, of course, has been dead for 10 years. These Radio 2 darlings are swelling the ranks of a genre that is becoming more popular by the day - the death duet. Time was, the dead stayed put. Now, with improvements in digital sound, grafting new collaborators on to old takes can be a seamless process. Ever-evolving visual tricks mean you can project a hologram of some long-gone great, and karaoke along with them.

But should you? The qualitative leaps in audio and video have been matched, it seems, by great leaps in philistinism and greed. Where once only blood relatives were allowed to dig up a star's out-takes and refashion them for a fast buck, now everyone is at it.

It was not the first, but the best-known posthumous duet of yesteryear is probably Natalie Cole singing 'Unforgettable' with her father, Nat 'King' Cole in 1991. Since then, the dead have been very busy, hanging out in the studio and heading out on tour. Here are a few of our dead 'n' alive 'favourites':
 

� In 1998 Elvis Presley's former band began a world tour in which they accompany a screen projection of the King. Last August Lisa Marie Presley duetted with her father on 'In the Ghetto' for Hurricane Katrina victims.
 

� Rapper The Notorious BIG, murdered in 1997, released an album of duets with Eminem, Jay-Z, R Kelly and Mary J Blige in 2005.
 

� Tommy Cash, brother of Johnny, is currently touring Ireland with a tribute show in which he duets with his late brother. Dweezil Zappa has toured his father Frank's old songs, with guest 'appearances' by Frank.
 

� Miles Davis's nephew released an EP of mixes this year which featured rapper Nas and guitarist Carlos Santana 'duetting' with Davis. A further duets LP is in the works.
 

� Jimi Hendrix's estate will not consider death duets. Rejoice!

Source: The Observer