Daphne Arnott was born in London, in December 1926. During the war she worked for the Hawker Aircraft Company and later went to St Georges Hospital, Hyde Park, as a nurse.
During 1948 she became an active member of the family engineering business, as a garage proprietor. Family associations with motorsport spurred on an enthusiasm to take part in competition, a prototype 500 was constructed in 1951 and Arnott Cars formed to series produce her cars, making her possibly the first female manufacturer. She followed the 500 with a 1,100cc, Climax powered, Arnott supercharged sports car which she took to the 1955 Le Mans. The event didn't work out that well Peter Taylor crashing in practice.