A graduate of the University of London, Andrews was awarded an assistant's position at the British Museum, after a competitive exam, in 1892.
Alfred Nicholson Leeds' gifts to the British Museum of Jurassic marine reptiles from the Oxford Clay of Peterborough elicited his interest in plesiosaurs and other sea-reptiles which culminated in a catalogue of the Leeds collection at the British Museum (2 vols.
1910-13); his interest in this area did not flag afterwards: his last, posthumously-published paper concerned the skin impressions and other soft structures preserved in an ichthyosaur paddle from Leicestershire.
In 1897 he was selected to spend several months at Christmas Island in the Indian Ocean, to inspect it before the activities of phosphate mining compromised its natural history.
[3] After 1900 his health began slowly to fail and he was sent to spend winter months in Egypt; there he joined Beadnell of the Geological Survey of Egypt, inspecting fossils of freshwater fishes in the Fayoum, where Andrews noticed mammalian fauna not previously detected and published Moeritherium and an early elephant, Palaeomastodon, followed by his Descriptive Catalogue.