Phillip's father was an expert in what field?

Phillip's father works as an oil refinery expert for the Royal Dutch Shell company. Phillip has a very close relationship with him, as he tells Timothy later on in the story. His father is a strong figure, yet someone who treats his son with respect; he is also extraordinarily brave, risking his life by going out on oil tankers in dangerous waters infested with German submarines. In a further sign of his bravery and heroism, Phillip's father stays behind on the island while allowing his family to flee to safety.
The relationship between father and son is so strong that it's not surprising that Phillip is initially so hostile towards Timothy. As well as showing blatant racial prejudice, Phillip clearly feels that Timothy just doesn't measure up to his father in terms of being a male role model. However, as the story progresses, Phillip comes to see Timothy as a man very much in the mold of his father.