William Henry Perrow was educated at Truro, Cornwall, and in 1884 set up in business as an electrical engineer there. He installed electric lighting and telephone equipment and also manufactured and repaired electrical apparatus. In 1896 he came to the Witwatersrand as resident electrician to the Knight Central Gold Mine, but resigned shortly afterwards owing to ill health. Starting his own business once more he specialized in X-ray and electro-medical work. From 1897 to 1901 he was resident electrical engineer to the Treasury Gold Mines Company and later held similar positions with the Henry Nourse Gold Mine Company and with its successor, Nourse Mines. He was responsible for the electrification of the whole mining plant of the latter company, from which he retired in 1916. He then settled in Cape Town and for a time was in business with his son, Ewart Vivian Perrow, also an electrical engineer, under the name W.H. Perrow and son.
Perrow became an associate member of the (British) Institution of Electrical Engineers in 1908 and was elected a full member in 1916. He was also one of the founders of the South African Institute of Electrical Engineers in 1909, and served as its president for 1917/8. In 1910 he published 'Notes on the application of electricity to medicine and surgery, with special reference to X-rays and high frequency currents' (Transactions of the South African Institute of Electrical Engineers, 1909-1910, Vol. 1(4), pp. 81-), a paper that received the institute's gold medal award. A later paper by him dealt with 'Bergonie's chair for obesity' (1915, Vol. 6(4), pp. 117-), while in his presidential address he described the early history of the induction coil (1917, Vol. 8(2), pp. 26-).
Perrow was married to Elizabeth Annie, born Vivian, with whom he had three sons and a daughter.