What, in your opinion is the best twist in the novel "To Sir With Love" by  E. R. Braithwaite?

I think the best twist in the novel comes in Chapter 11 during the Boxing match between Braithwaite and Denham as the match gradually reinforced Braithwaite's control over his class. After Denham's violence and attempt to combat his teacher, Braithwaite got angry and punched Denham in the solar plexus and won the fight. While such action is controversial and not suggested to be performed in today's times, Braithwaite's reputation increased in his class. His students now obeyed and respected him. This was hence a major turning point in the story.