Blash entered motorsport at the age of seventeen when he joined the RRC Walker Racing Team as a mechanic, working alongside established drivers Jo Siffert and Jo Bonnier. In 1968 he moved to Lotus, becoming the race mechanic for Graham Hill. He continued with the team under Jochen Rindt; during the 1969 Spanish Grand Prix weekend he accidentally cut portions of a larger front wing from aluminium panels, prompting Colin Chapman to threaten withdrawal of the cars — in the end Lotus raced and all three cars retired. Rindt's death during qualifying at the 1970 Italian Grand Prix prompted Blash to take on management responsibilities within Lotus before eventually walking out alongside several colleagues.
In 1973 Blash joined the Brabham Formula One team as team manager, a role he would hold until 1988. Working alongside owner Bernie Ecclestone and designer Gordon Murray, he oversaw one of the most productive eras in the team's history, including Nelson Piquet's world championship victories in 1981 and 1983. His tenure at Brabham established his reputation as a calm, experienced organiser in an era when the team manager's role demanded constant improvisation.
When Brabham was sold to Swiss financier Joachim Luhti after 1988, Blash moved to FOCA. After Luhti's arrest and the subsequent purchase of the team by the Middlebridge Group, Blash returned to Brabham as Sporting Director to rebuild the organisation, helping secure an engine supply from Yamaha for the 1991 season.
Blash's relationship with Yamaha grew into a long-term professional association. He joined the Japanese manufacturer as their sporting director, overseeing its engine partnerships with Jordan and later Tyrrell. Simultaneously he managed Activa Technology, a Yamaha subsidiary based in the former Brabham factory in Chessington that conducted research, development, and fabrication for the motor racing industry. He continued to run Activa while his work in the sport broadened into governance roles.
From December 1995 until the end of the 2016 season, Blash served as the FIA Deputy Race Director at all Formula One Grands Prix under Race Director Charlie Whiting. In this capacity he was present at every race on the calendar for more than two decades, helping apply and interpret the regulations on circuit, managing the complex logistics of race starts, safety car periods, and competitor relations with the stewards. On 5 July 2016 the FIA announced he would step down from the role at the end of that season.
From the 2022 Formula One season, Blash was appointed Permanent Senior Advisor to the Formula One Race Directors, returning to the paddock in a consultative capacity following the turbulent 2021 season and the controversies surrounding race direction at the Abu Dhabi Grand Prix. His experience spanning from the 1960s to the 2020s made him a uniquely qualified resource for the incoming race-direction team.
Alongside his FIA responsibilities, Blash has continued to act as a consultant to Yamaha's motorcycle racing programmes, including their World Superbike operations, maintaining an association with the company that stretches back more than thirty years to the Brabham era.
Herbie Blash represents a rare continuous thread through Formula One's transformation from the cottage-industry 1960s to the modern corporate era. Beginning as a mechanic who once accidentally caused a pit-lane crisis at Lotus, he rose to become a trusted team manager during Brabham's championship years and spent two decades as the sport's principal deputy referee on circuit. His longevity and institutional knowledge made him an invaluable figure in a paddock that changes its cast almost every generation.