Jo was a leader and inspiration in the field of melatonin and chronobiology. Her group developed a melatonin radioimmunoassay that opened the door to investigating this hormone’s functions, so as a young PhD student in Gerald Lincoln’s laboratory her work was the absolute gold standard. Jo was my external PhD examiner, her intellectual rigour, enthusiasm, and critical insight were outstanding. It was a pleasure to keep in regular contact throughout my career, usually at neuroendocrine or chronobiology meetings.  Her sharp thinking, support, and sense of humour were memorable. Jo leaves a great legacy in biomedical science, rest in peace.