Just hours before tens of thousands gathered for the Diamond Jubilee Concert, the palace announced that Prince Philip, the Duke of Edinburgh, had been hospitalized with a bladder infection.
"The only sad thing is that my father could not be here tonight," Prince Charles, heir to the throne, told the crowd at the close of the three-hour concert.
"But if we shout loud enough, he may just hear us in hospital," added Charles, triggering an immediate chorus of "Philip, Philip" from the concert audience of around 20,000, and an additional estimated 250,000 people who thronged The Mall, the royal avenue leading up to the palace.
The hospitalization of the Duke of Edinburgh cast a shadow over the four-day celebration of the queen's 60-year reign, which continues Tuesday with a thanksgiving service at St Paul's Cathedral and a royal carriage procession through the heart of the British capital.
Prince Philip, 90, was at the queen's side during a three-hour historic flotilla on the Thames Sunday. He would remain under observation in the private King Edward VII hospital for a few days as a precautionary measure, a spokeswoman said.
The duke suffered a chest infection in 2008. At Christmas 2011, he experienced a heart scare and had a coronary stent fitted in what was described as "minimal invasive surgery."
The jubilee concert was opened by Robbie Williams, singing his hit song Let Me Entertain You. Other performing artists, representing the six decades of the queen's reign, included Paul McCartney, Shirley Bassey, Elton John,Stevie Wonder and Kylie Minogue.//DPA