He made his official debut a few weeks later, when Tyrrell made the third car available for him at the Canadian Grand Prix. Because he took part in this event, Thackwell was often listed as the youngest driver to start a Formula One race, but this claim is arguable. On the first lap of the race, Alan Jones and Nelson Piquet collided at the first turn and were subsequently hit by a number of other cars, including Jean-Pierre Jarier and Derek Daly, both driving Tyrrells. Thackwell negotiated his way through the carnage and returned to the start/finish line undamaged by which time, the race had been red flagged. As both Jarier's and Daly's cars were too badly damaged to repair quickly, Thackwell was instructed by Ken Tyrrell to give up his car for Jarier. Under Formula One regulations, when the race is stopped after less than two full laps, the original start is declared null and void and the race starts anew. If a driver cannot bring their car back to the second start, they have technically not taken part in the Grand Prix. Using these criteria, Ricardo Rodríguez remained the youngest race starter until Jaime Alguersuari broke the record at the 2009 Hungarian Grand Prix; a record that was subsequently broken by Max Verstappen in 2015.