Grand National runner Celebre D'Allen tragically passed away from a 'severe bacterial respiratory infection' that emerged after the race. A post-mortem examination revealed that the horse's immune system was 'severely compromised' during the 'exercise-associated episode' on Saturday. Despite initially showing signs of recovery, the 13-year-old's condition deteriorated and he died on Tuesday. The incident has drawn criticism from animal rights groups, while the British Horseracing Authority is conducting a detailed review.