Describe symbolism in The Honourable Schoolboy by John Le Carre

In Chapter Eight, Jerry goes to the races, where he meets Drake Ko. He finds Drake to be open and friendly until he asks about the secret of his luck. Jerry also meets Tiu, a large, quiet man who escaped China in a boat with Ko. This escape is important because it will be revisited again as the plot develops. At this point, however, the escape is simply a symbol of Drake Ko's desperation to get out of China.