In October 1942, nine-year-old Clark made her radio debut while attending a BBC broadcast with her father. She was there trying to send a message to an uncle stationed overseas, but the broadcast was delayed by an air raid. During the bombing, the producer requested that someone perform to settle the jittery theatre audience, and she volunteered a rendering of "Mighty Lak' a Rose" to an enthusiastic response. She then repeated her performance for the broadcast audience, launching a series of some 500 appearances in programmes designed to entertain the troops. In addition to radio work, Clark frequently toured the United Kingdom with fellow child performer Julie Andrews. Nicknamed the "Singing Sweetheart", she performed for George VI, Winston Churchill, and Bernard Montgomery. Clark also became known as "Britain's Shirley Temple", and was considered a mascot by the British Army, whose troops plastered her photos on their tanks for good luck as they advanced into battle.