[1] He was educated at Pate's Grammar School Cheltenham and Christ's College, Cambridge.
He played several games for Bedouins, a 'touring' association football team that drew the majority of their players from universities.
Posnette made his name in West Africa, 1937-49, where his work helped preserve the cocoa crop through the development of the more disease resistant hybrid Trinitaro plants and led to him being dubbed 'the Father of Modern Chocolate.
[2] He returned to UK to work at the East Malling Research Station on solutions to disease in plants such as apples and strawberries.
He was also visiting Professor of Plant Sciences at Wye College, then part of the University of London.