Knussen composed a number of impactful, colourful and often playful works (mainly for musical ensemble or orchestra) during the 1970s that were widely admired for their ability to encompass a sense of fun and a high level of craftsmanship. Never pretentious, Knussen seems to have been universally popular among fellow composers and performers, and led the famous London Sinfonietta though one of its most fruitful periods in the 1980s.
During the 1990s he wrote, among other things, two "children's" operas, Where the Wild Things Are and Higgledy Piggledy Pop, both with libretti by Maurice Sendak. Both have proved popular and have been performed widely.