When Ken Tyrrell, the team's owner, became disenchanted with the poor performance of March chassis during the season, he decided he would design and build his own car. He employed Derek Gardner to design it in secret at his own house. Tyrrell had run Matra chassis in 1969, but Matra's acquisition by Chrysler made continuing to use the preferred Ford Cosworth DFV engines with the Matra chassis impractical. The project, codenamed "SP" which meant "Special Project" cost Tyrrell over £22,000 of his own money. The resulting car made its debut at Oulton Park at a non-championship race but retired; the car was introduced too late in the season to make any difference in the championship; it competed in the final three rounds of the season in North America. Jackie Stewart took pole in the Canadian Grand Prix but retired with axle failure while leading, Stewart led again in the United States Grand Prix when the car suffered an oil leak. The Mexican Grand Prix was delayed due to the large crowd of 200,000 proving difficult to control, almost forcing the cancellation of the race. They were crammed in front of the guard-rails, sat at the trackside and ran across the track itself. Despite impassioned appeals from Stewart and local hero Pedro Rodríguez they still remained troublesome. Stewart had suspension failure caused by running over a dog. Stewart took pole in the South African Grand Prix but finished 2nd to Mario Andretti's Ferrari, Stewart raced the Tyrrell 003 for the remainder of the season. Peter Revson drove the 001's final race in the United States Grand Prix but retired with clutch failure.