The case of Stephen Gallant, the convicted murderer, who carried out an act of outstanding bravery, in stopping a terrorist attack, whilst on day release from prison, is back in the news. It's being reported as if he was given a Royal pardon, but actually he has only been referred to the parole board, 10 months earlier than he would have been. He was sentenced to 17 years, in 2005, so he was going to be out soon anyway.
Nevertheless, it does appear that his parole hearing was fast tracked, thanks to a royal intervention. There is some mention of a royal perogative of mercy, which sounds like a kind of compassionate release. It does appear that he is being 'rewarded' for his bravery in a very small way though.
So that does raise some interesting questions, like would he have had a royal intervention, if he were an SO, rather than a murderer? It also suggests the possibility that someone could get their SHPO lifted early, for example, by performing an act of outstanding bravery.