Mars Bars are made by US company Mars, Incorporated.
The manufacturer also owns several other chocolate brands including Celebrations chocolate tubs, Galaxy, Hotel Chocolat, M&Ms and Maltesers.
It also owns non-chocolate brands including Dreamies, Hubba Bubba, Pedigree and Whiskas.
The company was founded in 1883 by Frank C Mars, from Minnesota, with his mother Elva teaching him how to hand-dip chocolate.
Mars Bars were first made by hand in Slough, Berkshire in 1932 and are still made in the town.
A Mars spokesperson said: “Over the last 35 years, we have made a number of updates to our bar sizes and pack formats to reflect consumer demand, alongside considering wider external factors such as manufacturing costs and the price of cocoa.”

