 Whilst at Cooper's he worked with Ivor Bueb, Roy Salvadori, Ken Tyrrell and Jack Brabham.Crosthwaite did the rounds of the manufacturers to find suitable engines and decided on a Coventry Climax (which he had seen on a front-engined Kieft) for low weight and small size, and a Connaught engine for power and compactness.He found the people at Coventry Climax keen to develop their engine and increase bhp.