My father, Jack Leonard, who has died aged 87, was an innovative and highly respected engineer and businessman. Under his leadership the company he co-founded, Eurotherm International, became a world leader in the supply of temperature control devices to chemical, glass, cable and aerospace manufacturers. Jack was born in Prestwich, Manchester, the son of Leonard Lazarus (who later changed his surname to Leonard by deed poll), a film distribution manager for Warner Brothers, and Cecilia (nee Phillips), a housewife. He…