It was first manufactured under the Mars bar name in 1932 in Slough, England by Forrest Mars, Sr., son of American candy maker Frank C. Mars. He modelled it after his father's Milky Way bar, which was already popular in the US. He had a staff of twelve people, and originally advertised it as using Cadbury's chocolate couverture. The bar and the proportions of the main components have changed over the years. With minor variations, this version is sold worldwide, except for the US, and is packaged in a black wrapper with red gold-edged lettering.