the original four-finger version of the bar was developed after a worker at york's rowntree's factory put a suggestion in the recommendation box for a snack that a "man could have in his lunch box for work". it was launched in september 1935 in the uk as rowntree's chocolate crisp, and the later two-finger version was launched in 1936. it was renamed kit kat chocolate crisp in 1937, and just kit kat after world war ii. since 1957, the slogan for the kit kat in the uk and elsewhere has been "have a break... have a kit kat".