There's been a major upset to the prison system today, with the Court of Appeal ruling [PDF] that parole boards can not consider deterence when determining whether to grant parole or home detention. Parole boards have been doing this for years, effectively re-sentencing prisoners based on public pressure and their assessment of how much punishment they deserved. But now, the game is up. The ruling could affect hundreds of prisoners whose decisions had been made illegally, and result in their being granted parole, or being able to sue for damages for being imprisoned for too long and in contravention of the law. And this would be entirely justified - the government (through its agents, the parole board) have been making decisions illegally, which has almost certainly resulted in people serving more time in prison than they were required to. If that is not worthy of financial compensation, I am not sure what is.
The worry is that the Prisoners and Victims Claims Act 2005 could apply here. Such claims certainly meet the first criteria for being a "specified claim" under the Act - concerning "an act or omission by or on behalf of the Crown" which affects the claimant "as a person under control or supervision". It would seem to depend then on whether they are brought as BORA cases alleging a breach of the right to liberty, or on some other basis.
Wrongful imprisonment is a clear injustice, regardless of who it happens to,and if the Prisoners and Victims Claims Act prevents compensation in such cases, then the law is fundamentally broken.