Who is Henning Hale-Orviston from The River Why and what is their importance?

Gus's father, Henning Hale-Orviston, is a famous angler and writer of fishing expeditions. Called "Hen" by his wife and "H2O" by his son, Henning is an avid fly fisherman and one of the leaders in the fishing industry on fishing with a fly. His relationship to fly fishing helps mold Gus with his own fly-fishing skills from the time he is a small boy. Although Gus questions whether his relationship with his father would be as strong if he were not a fishing prodigy, he does hold some respect for his father's knowledge and training.