The Queen has taken her seat in the royal box for her star-studded Diamond Jubilee concert, but was without the Duke of Edinburgh who has been taken to hospital with a bladder infection.
The musical tribute to the Queen has been overshadowed by the announcement, made a few hours before the show began, that Philip has been taken ill.
He is receiving treatment at the King Edward VII Hospital in central London and will be kept under observation for a few days.
Philip is said to be "disappointed" at not being able to attend the show, featuring some of the biggest names in pop.
Sir Paul McCartney, who was closing the concert with three songs, wished the Duke well, saying: "We all send our best wishes for a speedy recovery. I hear he's not too bad."
Take That star Robbie Williams opened the show by belting out one of his biggest hits, the aptly-named Let Me Entertain You.
Performers from the present generation also appeared on stage - Will.i.am Jessie J, JLS and Ed Sheeran.
But it was the veterans Sir Cliff Richard and Sir Tom Jones who got the crowds on their feet with renditions of classic songs from their repertoire.
Organisers said days before the concert that the Queen would take her seat at around 9pm. She arrived wearing a stunning cocktail dress of gold lame designed by Angela Kelly under a dark cape.
The dress had sweeping trimmings of antique gold lace and deep olive, and was adorned with Swarovski crystals.