British Princess Anne returned to her official duties today, Friday, less than three weeks after receiving treatment in a hospital for a concussion believed to be the result of a collision with a horse. Anne (73), the younger sister of King Charles and the only daughter of the late Queen Elizabeth, spent five nights in the hospital following what Buckingham Palace described as a minor head injury on June 23. Anne had to postpone her official engagements, including a planned trip to Canada. However, the princess, who is seen as the most diligent and active member of the royal family, resumed her duties today by attending the National Equine Association Championship for individuals with disabilities, held in southwest England. The princess, a horse enthusiast, has been a patron of this charity for over 50 years and has chaired it since 1986. Anne sustained her head injury while walking in Gatcombe Park, where her home is located. It is believed the concussion resulted from a collision with the horse's head or legs, although a royal source indicated that she is unable to recall what happened.