While butter is a natural product which has been in existence for thousands of years, margarine is a more recent initiative. Made using buttermilk, the watery by-product of actual butter manufacture, it was developed by a French chemist in the mid-19th century as a synthetic edible fat.

Because the material used to make it was not as rich as butter, margarine was generally cheaper to buy and became popular.

The old standard margarine-making process – or ‘hydrogenation’ - saw hydrogen added to buttermilk to make a semi-solid mass.

But the modern method sees oil-soluble ingredients (such as colours, flavours and emulsifiers) added to water-soluble ingredients (like brine, starch, milk proteins and whey). The two are mixed together to produce an ‘emulsion’, which is then pasteurised and chilled to produce a fat. The fat is then kneaded - or ‘worked’ – pressed into tubs and packed into cases to be taken to the supermarket.

However, as the production process is not as natural, additives are needed to ensure that the margarines or spreads don’t go ‘off’ as soon as they arrive in-store. They include antioxidants, emulsifiers, stabilisers, colours and preservatives. Because the key ingredients and goodness in the cream have been stripped out to make butter, extra vitamins are added in an attempt to make up the nutritional elements lost during manufacture.

Such was the concern about the way that margarine was made that early in the 20th-century, the US Government listed it as a “harmful drug” and restricted its sale before taxing it heavily and introducing a licensing system for those stores which wished to sell it. As a controlled substance, it became – like alcohol and tobacco – a target for bootleggers.