In England and Wales, the average life sentence prisoner serves around 15 to 20 years before being paroled, although those convicted of exceptionally grave crimes remain behind bars for considerably longer; Ian Huntley was given a minimum term of 40 years. Some receive whole life sentences which make it almost certain that they will die in prison; they can only be considered for release on appeal to the High Court, or in exceptional circumstances such as great age or ill health.