Inglis, Sir Claude Cavendish (1883–1974), irrigation and hydraulics engineer, was born 3 March 1883 in Dublin, sixth among seven children (six sons and one daughter) of Sir Malcolm Inglis, a wealthy gentleman, and Caroline Inglis (née Johnston), both of Scotland. Educated in Ireland and abroad, Inglis attended St Helen's School, Dublin (1892–6), Shrewsbury School, England (1896–1900), and TCD, where he received a BAI in 1905. He was a talented and active youth, playing both the cello and piano and serving as registrar of the Choral Society at TCD; he was also a scratch golfer, representing Ireland in several competitions, and he spent a period travelling through Australia. The latter whetted his appetite for life abroad, so in November 1906 he joined the irrigation branch of the Bombay public works department (1906–38), where he was assistant engineer in Sind on the Jamarao Canal (1906–9) and first inspecting assistant engineer in the operation of three of the department's subdivisions (1909–11). He was then transferred to Bombay Deccan as executive engineer on the Godaveri canals, in charge of introducing northern Indian irrigation methods to the area (1911–13).
In 1913 he was appointed to the Poona irrigation district, where he would spend the remainder of his years in India. He was firstly put in charge of the Nira canals and headed field research into waterlogging (1913–16), but his talent for research soon resulted in his promotion to director of a recently established special irrigation division, for which he initiated and directed studies on waterlogging, soil classification, and land drainage and reclamation (1916–27). After his successful results, he was promoted to superintending engineer of a newly created irrigation development and research circle (1927–38), where he spent nine years continuing his examinations of canals, flooding, rainfall, and land reclamation and delved further into agriculture, sewage, and fertilisation. When the Indian government expressed interest in establishing a central hydraulics research station, he pushed for the use of the one he had set up near Poona, and when his offer was accepted, he was appropriately appointed director of the new central irrigation and hydrodynamic research station (1938–45). For eight years he supervised research into irrigation barrages, river training, bank protection, water supply intakes, flow in alluvial channels, and the technique of reproducing the behaviour of rivers in models. As a director, he was a dedicated, efficient, outspoken, and sometimes ruthless man, who, for reasons of accuracy and perfection, tightly held the reigns of control. He may have been demanding, but he was passionate and energetic, and while many of his employees disliked him at one time or another, his energy and commitment were contagious and all benefited from his leadership. His dedication resulted in many advances in Bombay Deccan irrigation management, and he made notable contributions on river training and the use of hydraulic models with loose boundaries.
By 1945 his age forced him into retirement, and he settled in England to write a two-volume report summarising aspects of his work at the Poona research station, entitled The behaviour and control of rivers and canals with the aid of models (1949), during which time he also acted as an independent consultant for projects in England, India, and the Middle East. When the British government decided to establish its own hydraulics research station, his input was sought; however, when they proved unable to find a suitable director, he agreed, despite his advancing years, to assume the role (March 1947). As director of the hydraulics research station, Wallingford, Berks., he utilised the same authoritarian method that had served him so well in India, but now he was managing a staff of men and women in their twenties and thirties who were much less accepting of his dictatorial manner. He may have been aggressive and brusque, but he had respect for those who held their ground with him, and as in India, his excitement and enthusiasm were contagious and all respected his ability. By the time he retired for a second time (March 1958), the Wallingford research station had some fine buildings and decent equipment, but its scientific skills were no match for more successful stations in Holland and France. On retiring, he and his wife moved to Henfield, Sussex, to be close to his two nieces, and he continued to work as a consultant.
He was a Companion of the Indian Empire (1936), received a knighthood in 1945, and was made an FRS (1953). He was a member of the Smeatonian Society of Civil Engineers and many other international engineering associations; he sat on the council of the Institution of Civil Engineers (1947–52) and received an honorary MAI from TCD (1953). He married (1912) Vera St John Blood (d. November 1972) of Dublin, daughter of John Redmond Blood, a brewer from Malahide; they had one son, Brian St John Inglis (qv), a writer and broadcaster. As Inglis aged, his eyes grew progressively weaker due to cataracts; an unsuccessful operation left him blind in one eye, but despite the potential risks, in June 1974 he agreed to undergo surgery on the second eye. Although it was successful, his general health suffered as a result, and he died 29 August 1974 at the age of 91 years.
Inglis published widely on many topics including the training and control of rivers, coastal protection, irrigation, and model investigations. A photograph of him (dated 1946) by the Bassano Studio is in the National Portrait Gallery, London.