Expresso Bongo was MacMillan’s second foray into musicals (his first was choreographing John Osborne’s disastrous The World of Paul Slickey in 1958). A satire on the music business, Expresso Bongo had begun life as a successful West End musical in 1958. The following year it was made into an even more successful film starring Laurence Harvey and Cliff Richard, becoming one of the ten best-selling films at the box office that year. Its leading character is a sleazy theatrical agent on the lookout for fresh talent to exploit. He discovers a teenage singer named Bert Rudge in a coffee shop, changes his name to Bongo Herbert, and a star is born. Fame, a record deal and the inevitable recriminations follow.

Val Guest, the director, engaged Kenneth MacMillan to choreograph the strip-club dancers who appear in the film. Struggling at Shepperton Studios to get them to dance and sing at the same time, MacMillan complained; “It's the simplest routine. They may have looks, legs and tits, but they have no co-ordination.” Nevertheless for his efforts MacMillan earned more than he would have done in a full year at Covent Garden.