In 1928, Fleming noticed that an ignored sample of staphylococcus aureus had been attacked by a bacteria-busting mould, a discovery that would go on to save countless lives, and still does today.

But at the time, Fleming didn’t continue his research. Instead the baton passed to a brilliant team from the University of Oxford, led by Howard Florey, but they too struggled to develop a medicine. With World War II raging, British pharmaceutical companies were pushed to their limits to develop medicines. Florey sought American support, hoping that a collective effort would yield powerful antibiotics.

Fleming’s strain of Penicillin just wasn’t strong enough to mass produce so in desperation, the US Department of Agriculture imported soil samples from around the world, and asked Americans to donate mouldy food to their labs. It was hoped that the scientists could locate and develop a stronger mutant strain. One of their own lab techs, Mary Hunt, came up trumps in 1943 when she turned up for work one day clutching a mushy cantaloupe, which proved the key to success.

Cheered on by the US government, Pfizer Pharmaceuticals invested in a risky fermentation system to mass-produce this new strain of Penicillin, and it worked spectacularly. When the Allies landed on the beaches of Normandy in June 1944, their medics carried enormous quantities of the life-saving drug.

This article was first published by History Revealed magazine in June 2014.