Who is Denis LaFoote from Stephen Coonts' Deep Black and what is their importance?

Denis LaFoote is the real messenger due to meet Karr and Dean in the London park. Knowing that he was being watched, LaFoote hired Kensworth to stand-in. He is baffled by the murder and immediately suspects the French intelligence chief, Ponclare. LaFoote is seventy-two years old and hasn't been in England for many years. He is later killed by Donohue, who suffocates him.