The comments section on zerohedge updates that it was probably a whistleblower.
Just listening to Dr. Tim Ball and if his understanding of UK law is correct, the difference is extremely important. If the material was hacked, UK courts will not allow it. If from a whistleblower, it is admissible. Which would explain why Gavin and others from Day One insisted "Hackers" probably "Russian Hackers" did it.