Fowler was born in Evesham, Worcestershire, on July 29 1870. His father, also called Henry was a furniture dealer, and his family were Quakers. He was educated at Prince Henry's High School, Evesham, and at Mason Science College, Birmingham between 1885 and 1887 where he studied metallurgy. He served an apprenticeship under John Aspinall at the Lancashire and Yorkshire Railway (L&YR)'s Horwich Works from 1887 to 1891. He then spent four years in the Testing Department under George Hughes, whom he succeeded as Head of the Department.
Between 1895 and 1900 he was Gas Engineer of the L&YR, moving in June 18 1900 to the Midland Railway (MR). On November 1 1905 he became Assistant Works Manager, being promoted to Works Manager two years later. In 1909 he succeeded Richard Deeley as Chief Mechanical Engineer (CME) of the MR.
Along with Anderson, Fowler was responsible for the adoption by the LMS of the Midland's small engine policy. Various Midland standard types were built by the LMS, including the 4P Midland Compound 4-4-0, the 2P 4-4-0, the 4F 0-6-0, and the 3F 0-6-0T. The small engine policy resulted in frequent double-heading, as the locomotives were not powerful enough to cope with loads, and thus increased expense. Standardisation also left these standard locomotives with short-travel valves and small axle boxes, the former leading to inefficiency and the latter to frequent hot axle boxes.
In another departure from the small engine policy, several 2-6-0+0-6-2 Beyer-Garratts were acquired for the Toton-Brent coal trains but interference from Derby saw these receive standard small axles boxes and short travel valves with the result that they were poor performers.
Sir Henry retired in 1933, Ernest Lemon initially taking over as CME for a short period before William Stanier was head-hunted into the job from the Great Western Railway. Stanier was to reform LMS locomotive policy.
Sir Henry died in 1938.