The Crown prosecution against George Pell began the day by accidentally revealing the secret identity of its key witness, then spent the rest of the morning floundering to make its case.

By the time the Victorian Court of Appeal broke for lunch, the victims of clerical sex abuse that had gathered in Court 15 to hear why Australia's most senior Catholic prelate should remain behind bars were in collective despair.

“(Chris Boyce QC) is stumbling and bumbling his way through it ... and he is making mistakes," one court attendee told 7NEWS' Chief Reporter Chris Reason, who is covering the livestreamed case from inside the courtroom.

Watch the video above.

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“He is throwing the case away,” another lamented.

Reason said there was a lot of speculation the senior prosecutor had become "rattled" after a horror moment earlier in the day when he accidentally named one of Pell’s two sex assault victims.

The names of the victims are under strict suppression orders, and the surviving Pell victim had given his evidence to a closed court during the trial.

The live feed from the courtroom had to be halted and the words removed.

"The moment saw the entire court freeze," said Reason.

“The judges warned Boyce and assured the court that the name hadn’t been broadcast, but I think the general opinion of those in the gallery, and certainly the media, was that Boyce’s day didn’t get any better from there.

“He very much seemed to be struggling under the pressure of the case. I’ve never seen anything like it from such an experienced barrister.”

One victims advocate, who goes under the pseudonym Michael Advocate, told Reason he was furious with the breach.

“Eighty people in that courtroom now know the victim’s name, it will leak out," he said.

"The whole thing just compounds the pain for that victim. As if he hasn’t been through enough.

“All of us want to keep that history private, our privacy is everything. I can’t tell you how bitterly disappointed we are with what happened.”

Pell supporters outside Victoria's Supreme Court. Credit: AAP

Not a liar or a fantasist

Boyce appeared to start the day confidently, telling the three-judge Court of Appeal that the man who was sexually assaulted by George Pell at Melbourne's St Patrick's Cathedral 22 years ago was neither a liar nor a fantasist.

In what was the second day of the disgraced cardinal's appeal against his conviction on historical sex abuse offences against two cathedral choirboys in 1996, Boyce told the court that the credibility of the Crown's key witness had only increased as his testimony progressed during the trial.

Chevron Right Icon 'The evidence grew in stature'.

The witnesses' videotaped evidence and cross-examination lasted eight or nine hours, Boyce said.

"During that time ... it seemed as if the nature of the evidence grew in stature.

"If it’s a fantasy, one would expect at some point the cracks would appear."

And then the name slip - and Boyce's argument appeared to deteriorate rapidly into what many on social media following the livestream described as a slow train wreck.

George Pell arrives for the second day of his appeal at Victoria's Supreme Court Credit: AAP

Unanimous verdict

At certain stages the judges appeared to be helping the QC by providing case history, details, leading questions and suggestions on argument, Reason said.

Boyce told the court anyone who had doubts on the witness' reliability only had to look at his response, when asked, during cross-examination, why he never spoke about the abuse to the other choirboy (now deceased) who was also present and assaulted by Pell.

"The response you see there, the manner in which it's delivered, any doubt one might have had … is removed," Boyce said, adding that the jury, which delivered a unanimous guilty verdict, clearly had no doubts.

Chevron Right Icon 'How does that square?'

But when Justice Mark Weinberg pointed out that the witness’ same videotaped evidence had not had the same effect on the first jury – a retrial had to be ordered after two of the 12 jurors in the first trial could not be persuaded of the cardinal's guilt – Boyce seemed to falter.

"It's just that you make the point that this is so obviously compelling and so clearly reliable and truthful, I just wonder how that squares with the fact that another jury were not able to agree," Justice Weinberg said.

Boyce appeared at a loss to explain clearly.

“Bizarrely odd”

Pell is serving at least three years and eight months of a six-year sentence for crimes he has consistently maintained he did not commit.

He was convicted by a unanimous jury on December 11, 2018, on one count of sexually penetrating a child under 16 and four counts of committing an indecent act with a child.

Four of the five convictions relate to the offences committed in the sacristy on either December 15 or 22 in 1996.

The fifth conviction relates to an incident the Crown's chief witness said happened about a month later, where Pell sexually assaulted the witness in a corridor crowded with other choirboys and possibly at least one other priest.

Acting for Pell’s defence in the appeal, Bret Walker SC told the court on Wednesday that it was such “bizarrely odd conduct, disgraceful conduct” as to be implausible, if not unbelievable.

A protester outside the Supreme Court in Melbourne. Credit: AAP

On Thursday, Judge Chris Maxwell suggested to Boyce the improbability of a six foot plus archbishop pushing a choirboy against a wall and sexually assaulting him without anyone noticing.

“It’s more than just risk – it’s in the presence of potential witnesses who would be likely to look in the direction of the archbishop at the moment just because he was there,” Maxwell said.

Boyce said Pell’s presence might have been noticed by others, but not his offending, given his status and the clerical vestments he was wearing.

And if it was so improbable, he added, why would the witness make such a thing up?

“You answer your own question,” Maxwell responded.

A decision on the appeal could take anywhere between weeks and months to reach.

Pell's legal team has already indicated that if the appeal is unsuccessful, the cardinal will not appeal the sentence.

The court adjourned shortly after 4pm on Thursday, and the judges have reserved their decision.

Conctact Kelly Burke at kburke@seven.com.au