When Takehisa Yaegashi was put in charge of developing a hybrid petrol-electric engine for Toyota in March 1996 he was sceptical that the complex, heavy and expensive system could be mass produced by the deadline 18 months later.

Nine years later, with the second generation of the fuel-efficient hybrid Prius car selling as fast as it can be built, Mr Yaegashi is not just a convert to the technology. Within Toyota, far and away the market leader in hybrids, the soft-spoken engineer is revered as the "father of hybrid".