Dahl married American actress Patricia Neal on 2 July 1953 at Trinity Church in New York City. Their marriage lasted for 30 years and they had five children: Olivia Twenty (1955–1962); Chantal Sophia "Tessa" (born 1957), who became an author, and mother of author, cookbook writer and former model Sophie Dahl (after whom Sophie in The BFG is named); Theo Matthew (born 1960); Ophelia Magdalena (born 1964); Lucy Neal (born 1965). On 5 December 1960, four-month-old Theo was severely injured when his baby carriage was struck by a taxicab in New York City. For a time, he suffered from hydrocephalus. As a result, Dahl became involved in the development of what became known as the "Wade-Dahl-Till" (or WDT) valve, a device to improve the shunt used to alleviate the condition. The valve was a collaboration between Dahl, hydraulic engineer Stanley Wade, and London's Great Ormond Street Hospital neurosurgeon Kenneth Till, and was used successfully on almost 3,000 children around the world.
Dahl married American actress Patricia Neal on 2 July 1953 at Trinity Church in New York City. Their marriage lasted for 30 years and they had five children: Olivia Twenty (1955–1962); Chantal Sophia "Tessa" (born 1957), who became an author, and mother of author cookbook writer and former model Sophie Dahl (after whom Sophie in The BFG is named); Theo Matthew (born 1960); Ophelia Magdalena (born 1964); Lucy Neal (born 1965). On 5 December 1960, four-month-old Theo was severely injured when his baby carriage was struck by a taxicab in New York City. For a time, he suffered from hydrocephalus. As a result, Dahl became involved in the development of what became known as the "Wade-Dahl-Till" (or WDT) valve, a device to improve the shunt used to alleviate the condition. The valve was a collaboration between Dahl, hydraulic engineer Stanley Wade, and London's Great Ormond Street Hospital neurosurgeon Kenneth Till, and was used successfully on almost 3,000 children around the world.