In 1967 the rage in cigarettes was to make them longer. Chesterfield was one of the biggest brands at the time and they countered with the “Silly Millimeter Longer” as the brand and catch phrase. Chesterfield is named for Chesterfield County Virginia where much of their tobacco was grown. The brand is still made today but is mostly popular in Europe.
never smoked 1 but it was a catchy tune.