In pictures: Penicillin: The first 'wonder drug'

Alexander Fleming stumbled upon the antibiotic partly by accident in 1928.

During routine research he noticed a mould called penicillium had developed on a plate, killing bacteria he was growing nearby.

He named the antibacterial substance penicillin.

But it was another 12 years before the drug's properties were investigated further.

Photo credit: National Media Museum/SSPL