 Complete the following phrase:  When Ken Tyrrell, the teams 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 Matras 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 