James Ene Ewa Henshaw was born in 1924 in Calabar, South Eastern Nigeria, West Africa, into a large family, the youngest of nine sons. His father was of royal ancestry, descended from the Efik lineage in Calabar, where in the days before independence his importance gave him a position within the colonial Nigerian Legislative Council, an august lawmaking body.
Having been brought up by his eldest brother, Lawrence Eken Richard Henshaw, following the death of their father, James Henshaw was encouraged to continue his schooling at the Sacred Heart Primary School in Calabar. He then went on to Christ the King College, a secondary school in Onitsha, a well-known commercial center in what was then the Eastern region (now known as Cross River State) of Nigeria.
Upon graduation from Christ the King College, Henshaw traveled abroad to Ireland and in 1943 enrolled as a medical student at the National University of Ireland in Dublin. He took bachelor of science and bachelor of medicine degrees and in 1949 qualified as a physician. In 1954, Henshaw had the opportunity to pursue a course for specialized training in cardiovascular diseases and was awarded the T.D.D. degree by the University of Wales.
Henshaw’s professional practice as a physician began in earnest on his return to Nigeria in 1955, where he first served as a senior consultant in tuberculosis treatment for the government of Eastern Nigeria, in Port Harcourt, until 1978. From 1968 to 1972, he served as the First Controller of Medical Services in Cross River State. Thereafter he became medical consultant in thoracic medicine to the Ministry of Health at the chest clinic in his hometown, Calabar.
In 1973, Henshaw was appointed senior consultant on tuberculosis control at Rivers State, a post he held until 1978. He also participated in national programs connected with the medical profession in Nigeria and held membership in the National Council of Health (1968-1972) and the Nigerian Medical Council (1970-1972). In spite of his demanding professional commitments, Henshaw remained a family man. He married Caroline Nchelem Amadi in 1958; they had eight children.