James McGowan qualified as Bachelor of Arts (BA, London) and Fellow (by examination) of the Institute of Actuaries (FIA, London, 1883). He worked for some years as actuarial assistant in the life assurance business, while he also did actuarial work relating to friendly societies (associations providing life insurance, medical insurance and pensions) and acted as examiner to the Institute of Actuaries. In April 1890 he was appointed actuary to the government of the Cape of Good Hope, with special reference to the census of 1891 and to investigate local friendly societies. He was the first fully qualified actuary in South Africa. He compiled some special reports on the Cape civil service pension funds and on the friendly societies and building societies in the colony. Soon he was appointed also as registrar of friendly societies, under the Act of 1892. Around 1897 he became secretary to the Sinking Fund Commission, and later a member of the court of review on income tax under the Act of 1904. He held these positions to 1909, when he retired on pension. A paper by him on the calculation of the percentage deductions from salary for superannuation funds and pension funds was published in the Journal of the Institute of Actuaries (1902).
At the annual congress of the South African Association for the Advancement of Science held in Grahamstown in 1908 McGowan read a paper on "Mathematical methods applied to statistics". The paper was published in the association's Report of the meeting (pp. 401-404). Despite its promising title it consists of a short, semi-popular review of some early attempts, mainly by the Belgian astronomer L.A.J. Quetelet during the 1830's, to apply mathematical methods (such as calculating means and fitting functions) to interpret various types of statistical data - an approach which the author supported.