Glass Petri dish used at Beecham Research Laboratories

Glass Petri dish with base scored with a diamond glass cutter into 16 squares for 16 different pathogenic bacteria to test their sensitivity to the new semi-synthetic penicillins as part of the work of Shirley Stevens and Robert Sutherland's laboratory at Beecham Research Laboratories, Brockham Park, maker not marked, 1950-1960

In 1957, the team at Beecham Research Laboratories discovered that penicillin grown from mould has 6-aminopenicillanic acid. By tweaking its chemical structure, scientists created medicines to treat a wider range of bacterial infections, with fewer side effects. These are known as semi-synthetic penicillins.