John Booth has confirmed that he has left the Toro Rosso Formula 1 team.
Following the collapse of the Manor F1 outfit at the end of 2015, Booth joined the Italian squad in April 2016 as the its director of racing.
Prior to that he'd spent six years in charge at Manor, though its various guises, having entered Formula 1 with Virgin in 2010.
Booth joined Toro Rosso on a consultancy basis, which enabled him to continue working with his own team in the World Endurance Championship.
There, his team is this season stepping up into the LMP1 class, competing against Toyota with a customer Ginetta G60-LT-P1.
Toro Rosso currently sits sixth in the constructors' championship with 12 points, Pierre Gasly recording its best result of the season with fourth in China.
F1 heads to Azerbaijan this weekend for the fourth round of the 2018 season.