I'd be interested to know if Britain has an International Crime Law like Spain that allows them to try crimes not committed within their sovereign territory. If so, I'd say go for it. It is a crime in itself to conceal a crime and Cardinal Joe Ratzinger may certainly be guilty of that in two German and one American cases. If they could find a British case where he was directly involved in the dismissal of punishment and failure to notify local authorities this would be even better.
I don't hold out much hope for such a move on the UK's part, nor any other authorities part but, good god what a show that would be.
Walking into the Old Bailey in his flowing white robes with his hands cuffed behind his back. Papal mugshots on the internet. How delicious!