In 1905, Folland became an apprentice at the Lanchester Motor Company in Birmingham, he then joined the design staff at Swift Motor Company and then in 1908 he became a draughtsman at the Daimler Company. It was at Daimler that he developed his interest in powered flying machines. Folland worked at the Royal Aircraft Factory at Farnborough from 1912, where he was the lead designer on the S.E.5 during the First World War. He also designed the Ruston Proctor Aerial Target, an anti-Zeppelin pilotless aircraft designed to use A M Low's radio control systems.
Folland left the Royal Aircraft Factory in 1917, joining the Nieuport & General Aircraft company as chief designer., designing the Nieuport Nighthawk, which was adopted as a standard fighter by the Royal Air Force but did not enter service owing to the problems in development of its ABC Dragonfly engine. Not long after starting at Nieuport, Folland was joined by Howard Preston - a design and stress man - who was also to work with him later at Gloster and Follands. Nieuport & General ceased operations in 1920  and his services were taken up by the Gloster Aircraft Company, who had built Nighthawks under licence during the First World War, joining them in 1921.
Folland Aircraft ltd.
Folland left the company in 1937, following the takeover of Gloster by Hawker, feeling that Hawker designs would be favoured over his own. Folland purchased the British Marine Aircraft Company at Hamble, near Southampton, renaming it Folland Aircraft Limited.
Initially, Folland Aircraft was mainly involved in sub-contract work for other aircraft manufacturers particularly during the Second World War. Some 45 civil and military projects were offered by Follands to meet Air Ministry requirements. Only one - the Fo.108 - a flying engine testbed nicknamed the "Frightful" from its appearance, was accepted and 12 of these were built.
By July 1951, Folland was suffering from severe ill health and resigned as Managing Director being succeeded by the designer W.E.W. Petter who had left English Electric. Nonetheless he remained on the Board until his death on 4 September 1954. Three weeks earlier, Petter's Folland Midge, the precursor to the Folland Gnat had made its first flight. In his book, Sky Fever, Sir Geoffrey de Havilland describes Folland as becoming a recluse after he retired as managing director.
- 1891 Cambridge Census RG12/1287, Folio 64, p. 5.
- James 2007, p. 11.
- Flight 10 September 1954, p. 395.
- Lewis 1978, p. 101.
- Flight 19 August 1920.
- Lewis 1978, p. 120.
- Lewis 1978, p. 133.
- James 1971, pp. 7–9.
- James 1971, p. 38.
- James 2007, p. 157.
- James 2007, p. 160.
- James, Derek N. Gloster Aircraft since 1917. London: Putnam, 1971. ISBN 0-370-00084-6.
- James, Derek N. 'Fighter Master Folland and the Gladiators. Stroud, UK: Tempus, 2007. ISBN 978-0-7524-4397-3
- Lewis, Peter. The British Fighter Since 1912. London:Putnam, 1979. ISBN 0-370-10049-2.
- "Mr H.P Folland". Flight, 10 September 1954, p. 395.
- "Our Designing Staffs and Their Future: A Word of Warning". Flight, 20 August 1919, p. 907.