Maessen 's second pop single , " Knock , Knock Who 's There ? " was a cover version of Mary Hopkin 's entry in the Eurovision Song Contest 1970 . It was released on Fable Records in April 1970 and peaked at No. 2 . It co-charted with Hopkin 's version . During the 1970 radio ban , a major dispute between commercial radio stations and record companies , Hopkin 's version was not well known to Australian listeners . " Knock , Knock Who 's There ? " finished third on '' Go-Set '' s Top Records for the Year of 1970 and was the highest placed by an Australian artist . Maessen became the first Australian female artist to be awarded a gold record certificate for a single with sales of over 50,000 . She won the 1970 Logie Award for " Best New Talent " and in the '' Go-Set '' Pop Poll was voted in the top five as most popular female vocalist
Eurovision Song Contest 1970
Eurovision Song Contest 1970
Liv Maessen