 During the third series press launch in March 2007 , the production team was approached by Will Baker , Kylie Minogue 's creative director , about her appearing in the show . Executive producer Julie Gardner replied that Minogue could guest star if her schedule was free . Minogue officially registered her interest on 26 March 2007 and was subsequently given a one @-@ off role as the Doctor 's companion . Minogue 's appearance would allow the show to easily transfer the lead companion role from Martha Jones ( Freema Agyeman ) to " Penny " — the intended companion for the fourth series , eventually replaced by Catherine Tate as Donna Noble — and provide a " big name " star to appear in the Christmas special . Her casting was first reported in the News of the World in April 2007 . Davies initially dismissed the story , but Baker and Minogue contemporaneously confirmed she would star in the show . Her role was officially confirmed on 3 July 2007 . Both Minogue and Doctor Who had acknowledged each other before : " The Idiot 's Lantern " mentions Minogue as a real person ; and Baker , a fan of Doctor Who , included aspects of the classic series in Minogue 's tours : the <unk> Warriors ( from The Five Doctors ) in the Fever tour ; and the Cybermen in the Showgirl tour . 
