Sauber’s head of track engineering Tom McCullough is to leave the team at the end of this season.
The former Williams man is returning to join a UK-based team.
The 38-year worked for Panoz and Reynard before joining Williams as data engineer in 2002. He held several positions, including the role of chief engineer on the F2 project, and as a test engineer he was also in charge of driver development, working with the likes of Kazuki Nakajima and Nico Hulkenberg when they were third drivers.
He then became a race engineer, working with Hulkenberg in 2010, Rubens Barrichello in 2011, and Bruno Senna and third driver Valtteri Bottas in 2012.
He joined Sauber at the end of last year, where he was reunited with Hulkenberg.