William hails Sir David Attenborough's 'remarkable milestone' at 100th birthday concert 3 hours ago Steven McIntosh Entertainment reporter BBC Studios Prince William was seated next to Sir David Prince William has congratulated Sir David Attenborough on reaching a "remarkable milestone", as the broadcaster and environmentalist celebrated his 100th birthday. Sir David's seven-decade career was marked with a night of memories, live music and special guests at a special concert at London's Royal Albert Hall on Friday. "It is a rare privilege to celebrate a century of life," Prince William said, "but it is rarer still when that person has transformed the way we see the only home that we have - planet Earth." Meanwhile, a cast of helpers from the natural world helped deliver a card written by King Charles from Balmoral Castle in Aberdeenshire to Sir David's hands at the concert in London.…