Tom O'Brien was a race rider. British and Irish racing communities mourn his death at 39 after a cancer battle. Many publications called him a remarkable individual. O'Brien secured victories at the renowned racing event. The Guardian and 7NEWS reported his death after a courageous fight with cancer. At Bangor, a colleague called him a hero and a brilliant rider. Yahoo News Australia said O'Brien was the another rider to die in two days. Tributes continue in the world of horse racing.