" named after his prisoner number on Robben Island. Mr Mandela’s brother died of Aids.

Although it was perhaps unprecedented for a First Lady of a great power to sing at a pop concert, France appears to have developed etiquette for the event. Bruni did not hug " much less kiss " Stewart, either before or after their set, and barely swayed as she performed her songs. Her husband, sitting half way back in the glorious golden clam-shell that is Radio City Music Hall, clapped but did not budge from his seat when others rose.

As soon as she finished her performance, the couple left to catch a plane for France " drawing several previously unidentified secret service agents out of surrounding seats. Her early departure meant that she missed the grand finale, when all the artists danced rapturously together as Stevie Wonder sang Happy Birthday to Mr Mandela.

Stewart, who has been writing unpublished songs to Bruni’s French lyrics in recent years
. . .

. . . . has compared Bruni’s voice to Dylan’s — apparently a compliment. Where Dylan has a whiney edge, however, Bruni’s rasping is more like pillow talk. Quelqu’un m’a dit is an endearing solo in her breathy, feminine tones. But it left Stewart with little role but to ooh and aah in French during the chorus. It was hardly a duet.