Henry Albert Hoy (1855–1910) was a locomotive engineer with the Lancashire and Yorkshire Railway (L&YR). Hoy was born on 13 January 1855 in London, and educated at King Edward VI's Grammar School in St Albans, and at St John's College, Liverpool University.
In 1872 he began an apprenticeship under Francis William Webb at the London and North Western Railway's Crewe works. In 1878 Hoy transferred to the drawing office, where he designed continuous brakes.
In 1884 Hoy moved to the L&YR, becoming an outdoor assistant in the locomotive department under Barton Wright in Manchester; he was promoted to works manager a year later. In 1886 Hoy was made works manager at the L&YR's new works at Horwich. He worked principally on electrical engineering.
When John Aspinall was appointed General Manager, Hoy became Chief Mechanical Engineer. His principal contribution was the design of an electrification system for the Liverpool to Southport line, including motor bogies.
Hoy's only locomotive design was a twenty-strong class of troublesome 2-6-2Ts, built 1903–04, which became LMS nos. 11700-11716.
He conducted various other experiments. One of these was the use of a new brass alloy for making firebox stays. Its composition was 62% parts copper, 38% parts zinc and 0.37% of iron. This alloy was a failure. Despite being claimed to be more elastic, it suffered problems in service. In the worst of these, a fatal boiler explosion with a Class 30 0-8-0 near Knottingley in 1901 was caused by the failure of a number of firebox rod stays made from this alloy. These locomotives were an Aspinall design, but had been constructed during Hoy's tenure. On investigation it was found that the alloy was brittle enough to have cracked, even within the thickness of the copper plates of the firebox. Previously the boiler had given trouble with leaks from its stays, probably from early cracking, and where the heads of the stay had been hammered to caulk this, this had caused the heads of the stays to crack. The size of the firebox waterspace was also criticised, although this was due to Aspinall's standard boilers, rather than Hoy's construction. A waterspace of only 2 1⁄2 inches (64 mm) was narrow, but not unique for contemporary practice. The L&Y did though make it a policy to provide a waterspace of 4 inches after this, even at the cost of a reduction in grate area.