John Lloyd was born in South Wales in October 1888. He was educated in Staffordshire and subsequently worked in a steel mill studying the stresses in metals. Widely known as "Jimmy" he became a leading aircraft designer, pioneering the use of steel for propellers and sea-plane-floats and being pre-eminent in the use of alloys in design. On the outbreak of the First World War, Lloyd joined the Royal Aircraft Establishment, Farnborough, as Head of Stress Calculating and Design. In 1917 he joined the Siddeley Deasy Company as Chief Designer. He was subsequently Chief Designer (1923-48) and Technical Director (1948-55) of Armstrong-Whitworth, where he worked until his retirement in 1959.

As a designer he was often well in advance of his time. In 1918 he produced the Siskin, for many years a mainstay RAF fighter, and in 1924 produced the first all steel aircraft in Britain. He designed the Atlas seaplane, the three engined Argosy transport used from 1926-35 by Imperial Airways, the four engined Atalanta, the Whitley Bomber used in World War II and the Albemarle used at Arnhem to carry troops and supplies.

He was elected a Fellow of the Royal Aeronautical Society (FRAeS). Lloyd died in 1978.