Katherine Jenkins and Dame Kiri Te Kanawa kicked off Queen Elizabeth II's coronation anniversary celebrations by performing for the British monarch at Buckingham Palace on Thursday night (11Jul13). The royal is marking 60 years since she was crowned Queen by hosting a four-day festival at her official London residence, Buckingham Palace, and the event was launched on Thursday with a night of music and dance. The two opera stars were among the performers, along with dancers from English National Ballet, while the Queen and her family were in the audience. Charles, Prince of Wales was in the royal box, along with the Queen's granddaughter Zara Phillips, who made her first public appearance since announcing her pregnancy this week (beg08Jul13). Catherine, Duchess of Cambridge, who is due to give birth imminently, was notably absent, along with her husband, Prince William, who is currently in Wales on duty for his job as a search and rescue helicopter pilot. When asked about the impending birth, Prince Charles told reporters at the event, "Well, it won't be long now," while his wife Camilla, Duchess of Cornwall, added, "Yes, we are very excited, immensely looking forward to it and waiting for the phone call." Following her performance, Jenkins wrote in a post on her Twitter.com page, "Such an incredible night. Loved the finale with (choir) Only Boys Aloud - great to sing with you again!" Other artists on the festival bill include Katie Melua, The Feeling and Russell Watson.