[2][3] Cox was born to parents who worked as government servants, in the Post Office telephone engineers' department.
He was promoted to senior principal scientific officer in 1951, and ended his career as deputy keeper of the museum's Palaeontology Department, retiring in 1963.
His work at the British Museum has enabled him to study material from almost all parts of the world, and the results of his researches have been published in the transactions of learned bodies in at least ten countries.
Although his contributions to Mesozoic and Cainozoic Palaeoconchology are widely recognised as important and sound, his work on the Jurassic Lamellibranchiata is outstanding.
In addition to his systematic studies, he has made illuminating researches of an historical kind, especially in respect of the life and work of William Smith.