LONDON, June 6 -- When Stephen Parkinson, Britain's director of public prosecutions, stood before reporters on Thursday and said the investigations into Andrew Mountbatten-Windsor and Peter Mandelson would likely take more than a year to complete, he was not, he insisted, signalling any lack of urgency. He was signalling complexity. And he was, whether he intended to or not, confirming what many of Jeffrey Epstein's survivors have said for years: that the machinery of formal accountability moves slowly, if at all.

The two investigations are the most consequential criminal inquiries Britain has opened in connection with the Epstein files. Mountbatten-Windsor, the former Prince Andrew and younger brother of King Charles, was arrested in Fe...