I’m sorry to disillusion you, but the Queen has no power to intervene in this or any other judicial matter. I’m confident, however, that she, like the rest of us, has this desperately sad case in her prayers.
The Queen has enormous moral power to sway thinking, as well as political power—don;t kid yourself.
The Queen is not powerless nor is she an anachronism.
The levers of power in England are arcane and mostly unseen.
For her to have the power to do good but do nothing, is a grievous sin against God.