Queen Elizabeth II and Prince Philip (Creative Commons)

With a crowd of 18,000 gathered at Buckingham Palace, Queen Elizabeth II's Diamond Jubilee went on as planned Monday evening though the festivities took pause when the queen's husband- Prince Philip, the Duke of Edinburgh- was hospitalized.

Philip, who will be 91 on Sunday, was taken to King Edward VII Hospital for a bladder infection and will remain under observation for a few days. He will likely miss Tuesday's Diamond Jubilee finale, a spokeswoman for Buckingham Palace reported.

"He is, understandably, disappointed," the palace said. Paul McCartney spoke to fans outside Buckingham Palace after the news of Philip's hospitalization to wish the prince "a speedy recovery."

According to CNN, Philip was last hospitalized in December for a blocked coronary artery and said last year that he would "wind down" his work load and responsibilities.

"I reckon I've done my bit. I want to enjoy myself now ... have less responsibility, less frantic rushing about, less preparation, less trying to think of something to say," he told the BBC in an interview.

Originally the prince of Greece and Denmark, Philip renounced his title in 1947 when he became a naturalized British subject. He and Elizabeth married the same year after having met in 1939 when he was part of the Royal Navy. He then retired from the navy to support Elizabeth and focus on charity work when she became queen in 1952 following the death of her father, King George VI.

Continuing the celebration of Queen Elizabeth's 60-year reign, Monday's concert line-up at the Buckingham Palace includes performances by Elton John, Stevie Wonder, Robbie Williams, Kylie Minogue, JLS, Jessie J and more, according to the Metro Live Blog.

A chain of beacons will also glow around the world for her.

The beacons signify Britain's oldest signaling system, reported The Guardian, as well as a token of respect for the queen. A total of 4,200 beacons will be lit Monday evening, starting with the first in New Zealand.

• Bruno Peek, pageant-master of the beacons at the 2002 golden jubilee and now again, said: "We set out to mark the year by having 2,012 beacons worldwide, which would have been the most ever for this type of occasion.

• "To have reached double that figure reflects the national and worldwide respect and affection for the Queen and the desire to celebrate her 60-year reign."