Polfoto 21-06-2003 EMBARGOED: Not for publication before 0001 Sunday June 22, 2003. Prince William plays the marimba as the Shakarimba band, who have been flown in from Botswana to play at the Prince's 21st birthday on Saturday evening, rehearse Friday June 20, 2003, in the Queen's Guard Chamber at Windsor Castle. The prince has chosen an "Out of Africa" theme for his party and the more than 300 family and friends who have been invited have been asked to wear fancy dress. Watch for PA story. PA Photo: Phil Noble / WPA solo rota.