Britain's Prince William is taking flak for going on a ski holiday instead of attending a major royal engagement with his family. Criticism mounted after footage emerged of 34-year-old William busting late-night dance moves in the Verbier, Switzerland, this week. It has fueled claims from the tabloid press that the second in line to the throne does not work hard enough. The tabloid Sun used the headline "Throne Idle.'' William was skiing while his 90-year-old grandmother Queen Elizabeth II and other senior royals attended a Commonwealth Day service in London on Monday. An official record of royal engagements says William has carried out royal duties on 13 days this year, compared with 18 for Prince Harry and 24 for the queen. William also works part-time as an air ambulance pilot.