When Prince William arrived with Kate at Buckingham Palace yesterday for the Queen's annual luncheon, driving his black Range Rover, he was wearing a face of such thunder that even the serried ranks of royal reporters, well-used to William's occasional grumpy days, were surprised by his openly irritated manner.

Now we are learning that it is not just sleepless nights looking after Prince George that may have unsettled his mood.

The media have been on alert all this week that 'bombshell' royal evidence was due to be dropped in the hacking trial against former workers of Rupert Murdoch's now-shuttered News of the World newspaper.

That evidence finally came out today—according to prosecutors, Kate and Harry's phones were hacked and voicemail messages from William calling Kate 'babykins' are now making headlines around the world—and it must be horribly discomfiting for William, who loathes the press anyway, and sees them as responsible for his mother's death, to be reminded once again of just how thoroughly his private life may have been invaded by the rapacious media organization that was the News of the World. In another message described to the court by the prosecution, a voicemail was allegedly left in a falsetto voice on Harry's phone, pretending to be his girlfriend Chelsy, and calling him 'the best-looking ginger' ever seen.

As the reporters covering the trial knew the messages were might be coming, it is certain that William did too, and this may well account for his stressed-out mien yesterday.

There is a bitter irony unlikely to be lost on William in all this, which is that thanks to legal privilege and the requirements of an open justice system, transcripts of voicemails that would never have been published in the News of the World are now being read out in court (albeit heavily redacted at times). The same applies to the story that Chelsy reportedly "blitzed" Harry with calls and texts while he was training at Sandhurst, and the story that the Queen was allegedly annoyed about her bowls of Bombay Mix and cashew nuts being 'scoffed' by Royal Protection Officers, and went round 'checking levels' in the bowls. Neither story was actually published by the News of the World, but both have now become firmly established in the public mind as truthful because they were read out in court.

So we perhaps now have a better idea why the second-in-line to the throne has been in such poor humor recently.

By another irony, today's session was the last time the court will hear evidence before packing up for the holiday season. Today’s parting shot from the Old Bailey served as a graphic reminder of the many reasons William and Kate have to feel hounded by the press—and this final day has certainly left William and Kate with a most unwelcome Christmas present.