歡樂今宵
Koo joined TVB as their director of music in 1973, where from the late 1970s until immigrating to Canada in the 1990s, he collaborated with the lyricist Wong Jim on many memorable TV theme songs. Koo has composed over 1,200 songs in his career, many of his songs are now considered as classic Cantopop. He only has 2 notable works as a lyricist, but they are both very short in length and total number of words. One was a children's song about the ten numbers, the other was the ending 'Goodnight' jingle for Enjoy Yourself Tonight.