His background is shrouded in mystery, as are a number of elements in the novel, and is only explained later
He is not English, but German
His family moved to England in 1935, most probably to escape persecution
His father is a German Jew and his mother is English
He feels inferior to his friend Keith, who goes to a better school and his family are a higher class than his
He is very much a follower and does what he is told to do, to the extent that he gets too involved in their spying game/ action
He grows up a lot in the novel as he realises that things aren't as they seem
He has sexual feelings too, as Barbara awakens his adolescence
He is an outsider and it seems he is bullied at school