Prince Charles (search) and his companion, Camilla Parker Bowles (search), stepped out together at a reception celebrating the prince's charitable work.

The couple, whose relationship has grown increasingly open over the last few years, arrived together at St. James's Palace for the champagne reception Monday in honor of the Prince's Trust, a charity that helps underprivileged youngsters.

The prince saluted the trust's celebrity "ambassadors" from the worlds of music, drama and fashion, including "Pop Idol" (search) winner Will Young, soul singer Jamelia and Queen guitarist Brian May.

Charles and Camilla, both of whom are divorced, have been cautious about launching their relationship in public since the death of Princess Diana (search) in 1997. Parker Bowles has been increasingly seen at the prince's side, but joint appearances at official functions have been few -- because their relationship has not been formalized and out of deference to Charles's mother, Queen Elizabeth II (search).

Parker Bowles, wearing a black lace summer dress, sat at a table with the prince to listen to performances from young musicians assisted by the charity, including Sarah Bennett, 25, who performed "Thunder in the Rain."

"It's about being in love with someone and it not being the right time, which I am sure we've all been there and can relate to somehow," she said.