In March 1970 , Hopkin represented the United Kingdom in the 1970 Eurovision Song Contest , achieving second place with " Knock , Knock Who 's There ? " Although she gave a confident performance and sang in a crystal-clear voice , and despite being the pre-contest favourite , Hopkin lost to " All Kinds of Everything " , performed by Irish singer Dana . Produced by Mickie Most , " Knock , Knock Who 's There ? " was released as a single on 23 March 1970 and peaked at number 2 in the UK . It was a worldwide hit , selling over a million copies
1970 Eurovision Song Contest
Eurovision Song Contest 1970
Mary Hopkin