Down to the Royal Courts of Justice again, those bizarre fairytale towers in the middle of the Strand, their gravitas all gone the moment you learn they were created in the 19th century, the modern state wrapping itself in ancient stone.

And all the more ridiculous when the star turn of the day is Sienna Miller.

Yes somewhere inside the building was the Leveson hearings, the judicial inquiry that has become some weird simulacrum of the thing it is investigating, with the celebs, stars, and “ordinary folks thrust into tragedy” bursting out of the red-top front pages and into the witness box.

Round the iron gates, hopeful papps were gathered, though most of the stars appear to be coming in through various underground tunnels at the back. Nevertheless, their presence is largely ceremonial in any case, a guard of honour much in keeping with the mediaeval pomp.

Then there’s the punters. The folks who turn up for the public galleries are a distinct type in any case — either concerned citizens auditing for the public good, early retirees and Rotary types with time on their hands. Or the plainly whacko.

With Leveson, there’s a third group crowding out the other two: the simply star-struck, people who are, dare one say it, less than fully enagaged with the debate about limits to press freedom.

The entrance and security procedures of the courts are irritating enough to frequent visitors; to those attending for the star power, they are ultimately baffling. One experienced group makes a break for the courtroom as soon as the gates open; others wander this neo-Gothic pseudo-cathedral for hours, ghosts of the general public among the periwigged barristers, and the judges who have to be told what the internet is, and that Audrey Hepburn is dead.

Your correspondent, it must be said, legged it back to Bar Italia, where they were playing it on the big screen. By the time I got there, the fair Sienna, very much the star of the show, was appearing.

Over the past few days, as the celeb witnesses have rolled out for the inquiry, we’ve heard a few extraordinary things. The first was a celebrity being reasonable — a surprisingly baggy looking Hugh Grant on Tuesday, whom the inquiry’s lawyers spent a lot of time trying to tempt into an A-grade tanty.

Grant didn’t play, coming straight out and saying that the press should have been all over him about the Divine Brown affair, and that he was objecting not only to illegal phone tapping but also to the manufacture of outrage based on false or miscontextualised information.

He also cracked off the first great quote of the week, referring to the notion that stardom made your entire life public property, noting that it was like saying: “You sold me your milk, you sl-t. I’m now entitled to help myself to your milk for ever.”

Grant was a lot more sure-footed than Steve Coogan (Alan Partridge) who came a day later, and sounded whiny and self-righteous. And he had come after the first witnesses, the Dowlers, parents of a murdered girl whose phone had been hacked, whose evidence had reminded everyone as to why the inquiry was necessary.

News Corporation’s attempt to tough out the scandal had collapsed when the Dowler case had been made public — and it was revealed that hacking the girl’s phone had led her parents to believe she might still be alive.

That news had been stomach turning and it had not diminished when Milly Dowler’s mother took the stand to relate how they had tried to call her phone repeatedly while she was missing only to find the voicemail full. Then one day it wasn’t, and as Mrs Dowler related, sparing us none of her initial sense of restored hope: “Oh thank God, she’s alive!”

She wasn’t of course — the voicemail had been emptied by someone at News of the World. It had been presumed to be detective Glenn Mulcaire, but he issued a statement to deny that he had done it.

That recalled, re-enacted moment reminded everyone why the inquiry was there in the first place — a sense that News Corp and perhaps other tabloids had pushed beyond sharp practice and into a destructive nihilism.

That was reinforced the next day, after the Grant interlude, with the McCanns, whose daughter Madeleine was abducted in Portugal four years ago. The Dowlers got a rough ride, but boy did they go to town on the McCanns. They were filleted and f-cked up by a relentless campaign of fabrication around every stray bit of disinformation to be found.

The McCanns eventually took a half-million pound settlement and a full-page apology from The Daily Express, but there had been limited sympathy for them from many quarters.

There had initially been limited sympathy for the couple. They had understandably used every opportunity to keep the story in the media, and the fact that Kate McCann was easy on the eye was of immense help.

But the story was turned eventually as the press required new angles — Kate McCann’s diary was published, after being leaked by the Portuguese police, stories were run suggesting that there had been orgies at the holiday where Madeleine disappeared, that the McCanns were having IVF treatment to generate a “replica” Madeline, etc.No tone was left unlowered, much of it done by papers other than News Corp, and all of it utterly baseless; UK tabloids effectively descending to the Weekly World News level, but with real people.

So when Sienna Miller took the stand today, it was assumed that this would be a fluffy end to the week. There’s probably people less in need of sympathy, but it’s hard to bring any to mind than this posh blonde British-American third-rate actress rocketed to the top.

Yet in her own quiet way it was Miller who brought home the routinised nature of the mad state of British tabloid media, noting that the disarray sowed by repeated revelations from hacked material had caused a collapse of trust among her family and friends, that papps had spat on and hurled abuse at her, and then delivered the line of the week: “I was a 21-year-old girl and there were times when eight large men were chasing me down dark alleys — and because they had cameras it was thought to be alright.”

Should some form of regulation come from this — not something I’m necessarily in favour of — it may be the combination of that line plus the McCann/Dowler tetimony that does it. If that’s the case then it will be the tabloids, and especially News Corp, who’ve made it happen, because they’ve abused the leeway we appear willing to extend to the press for the pursuit of real public interest matters.

Workplace cultures have been created which reinforce not merely indifference to basic social values, but a certain sadistic elan, which becomes not merely self-perpetuating but self-selecting — eventually the people on the front line at an organisation like News become those most attracted by a license to bully, and a collective ethos based around that. Nothing the other tabloids have done, in volume or scope, really compares with News’ descent into the lower depths.

Throughout the inquiry various witnesses were asked of their solutions to the problem, and their view of the Press Complaints Council. In so far as people even thought of its existence, they had none, and no-one does — because the tabloid behaviour has been so sociopathic as to put us in the quandary of how to represent moral values in a regulation system if those being regulated have lost the category of morality entirely.

Doubtless, at the end of the day, those who had come for the celebrity extravagaza were still wandering confused in the stone, empty halls of the Law — as as we all, and likely so to do for some time.