Herd was born in 1939 and showed early academic aptitude, turning down an offer to play cricket for Worcestershire at the age of 18 to pursue higher education. He entered St Peter's College, Oxford, on a mathematics scholarship but switched disciplines and graduated with a double first in physics and engineering. He joined the Royal Aircraft Establishment in 1961, working as a design engineer on the Concorde project with a focus on computational fluid dynamics. He was promoted to senior scientific officer at the age of 24, an indication of the speed of his professional advancement in that field.
In 1965, Herd was recruited by McLaren after a tip-off from Alan Rees, a former school friend and racing driver who would later become his business partner. At McLaren, Herd worked on a range of projects including the Mallite-bodied M2A test car developed for Firestone. The M2A was the predecessor to the M2B Formula One car. During his time with McLaren he designed the M4B, M5A, and M7 Formula One cars, as well as the M6A that dominated the Canadian-American Challenge Cup series. He left McLaren in 1968, moving to Cosworth to work on a four-wheel drive Formula One concept. He also carried out work for Frank Williams in late 1969, modifying a Brabham BT26 to accept the Ford Cosworth DFV for Piers Courage.
In 1969, Herd co-founded March Engineering alongside Max Mosley, Alan Rees, and Graham Coaker. The name March was drawn from the initials of the four founders. The constructor entered Formula One in 1970 and competed until 1992, completing 207 World Championship Grands Prix and winning three, with four pole positions across the programme. March also achieved significant success in Formula Two throughout the early 1970s and made a prominent transition into Indy car racing in the 1980s: March cars won the Indianapolis 500 for five consecutive years from 1983 to 1987, a sustained dominance that demonstrated the team's adaptability across different disciplines.
Herd's design contributions within March included the controversial 721X of 1972, which concentrated mass at the car's centre using an Alfa Romeo transverse gearbox in an attempt to reduce rotational inertia. The concept failed in practice due to incompatibility with the Goodyear tyres of the period, generating chronic oversteer and understeer. The team's response — the 721G, built in nine days from a Formula Two chassis — became one of the more remarked-upon rapid recoveries in early 1970s Formula One.
Herd was appointed Commander of the Order of the British Empire (CBE) in the 1986 New Year Honours, recognised in his role as managing director of March. From 1995 to 1998 he served as Chairman of Oxford United Football Club, overseeing the team's promotion to Football League Division One in his first season in the role. He died from cancer on 4 June 2019 at the age of 80.
Herd's career bridged aerospace and motorsport at a moment when the skills of one transferred directly to the other. His work on the Concorde project gave him a grounding in aerodynamic analysis that was still relatively rare in racing car design in the mid-1960s. At McLaren he contributed to some of the most successful sports car and Formula One machinery of the era. At March he helped build one of the most commercially productive customer-racing constructors in Formula One history, one that sustained itself across two decades by combining factory ambition with reliable customer products and eventually extending its reach to the United States. The five consecutive Indianapolis 500 victories between 1983 and 1987 remain among the more durable records in American open-wheel racing.