Arnott was born in 1915 in London, and went to Sheringham House School and St Paul’s School in London. He matriculated at Pembroke in 1934, and graduated in Classics. During his time at the College he played water-polo. In 1961 he received his PhD from London University. Throughout his career, Arnott travelled West Africa and scientifically studied many of the West and Central African languages, primarily Fula and Tiv. Arnott was a member of the Africa Department at SOAS from 1951 to 1977, during which time he was appointed Professor of West African Languages. He died in Bedale, North Yorkshire, in 2004.