Meghan Markle has agreed to pay £67,000 in legal costs after losing the first round of her battle against the Mail on Sunday's publisher.
The duchess is suing Associated Newspapers Limited (ANL), publisher of the newspaper and MailOnline, over an article published in February 2019 which reproduced parts of a handwritten letter she sent to her father.
But in May, the High Court's Mr Justice Warby struck out parts of the Meghan's claim, including allegations of 'deliberately stirring up' issues between her and her father.
A written submission from July 22 has since shown that the duchess has agreed to pay in full the publisher’s costs for the strike-out hearing of £67,888.
The hefty bill was revealed as the court heard Meghan believes naming the five female friends who briefed People magazine about her and a letter sent to her father Thomas would be an 'unacceptable price to pay' for pursuing a claim against Associated Newspapers.
The Duchess of Sussex has applied for an order to keep secret the identities of the women, all 'young mothers', at a hearing at the Royal Courts of Justice in London.
Today a skeleton argument presented to the court by Meghan's legal team said: 'To disclose their identities to the public at this stage is an unacceptable price to pay for the right to pursue her claim for invasion of privacy'.
But in an embarrassing moment during the application Meghan's QC Justin Rushbrooke accidentally said the surname of one of the five friends the Duchess of Sussex is seeking to keep anonymous.
Judge Mr Justice Warby, who is expected to rule on the matter in August, immediately directed that the individual's name was not to be reported.
The five women were named as the sources of a People Magazine article in 2019 in legal papers submitted by Meghan to the court earlier this month, although their identities were not made public.
The People article lies at the heart of her privacy and copyright case against the Mail on Sunday because it was the first time the existence of a letter the Duchess had written to her father Thomas was revealed.
In response Antony White, QC for Associated Newspapers, the publisher of the Mail on Sunday and MailOnline, told the court that the principle of open justice in Britain means the five friends should be named. Mr White also said Meghan was apparently 'pleased ... with her friends' intervention' in speaking to People magazine, apart from the reference to the letter she wrote to her estranged father.
He said: 'There is no proper evidential basis (for the application). There is no evidence at all from four of the five friends and the evidence from the fifth (Friend B) has been shown to be unsatisfactory.'
Mr White said: 'There is no risk of reprisal in this case.' The barrister added: 'The information they disclosed to People was information about the claimant, but is not said by her to be private or information that she seeks to protect.'
The Mail On Sunday claims that revelations in People and the misleading impression it gave of the letter gave Thomas Markle the right to publish more of the handwritten note in the newspaper to defend himself after their relationship became hopelessly estranged in the wake of Meghan's marriage to Harry in May 2018.
But Meghan insists that she had no idea any of her friends had spoken to People magazine until after the fact.
All five of the women face the prospect of being hauled to the High Court in London next year to testify in the explosive privacy trial. They could be asked to confirm on oath whether the Duchess had no prior knowledge that they were going to speak to People.
Neither Meghan nor Harry attended the hearing at the Royal Courts of Justice in London today.
ANL's lawyers are resisting the application to keep the identities of Meghan's friends secret, claiming the duchess's friends brought the letter into the public domain when it was referred to for the first time in the People interview.
In written submissions, Antony White QC, acting for ANL, said: 'The friends are important potential witnesses on a key issue.
'Reporting these matters without referring to names would be a heavy curtailment of the media's and the defendant's entitlement to report this case and the public's right to know about it.
'No friend's oral evidence could be fully and properly reported because full reporting might identify her, especially as there has already been media speculation as to their identities.'
Mr White also said the present order sought by the duchess's lawyers would leave Meghan entitled to disclose the identities to anyone - including the media - who could publish it, while ANL's titles would remain barred from doing so.
Meghan's barrister Justin Rushbrooke QC said Meghan's five friends were entitled to 'a very high level of super-charged right of confidentiality' and confidential journalistic sources.
He claimed 'there is ample evidence before the court' to support his client's application to maintain the anonymity of her five friends.
He said: 'We say at least four of the five sources have no real role at all on the issue raised by the defendant's defence regarding the interview with People magazine in the US.'
He added that one of the five, known only as Friend B, had provided a witness statement to the court in support of the application.
Mr Rushbrooke said Friend B was 'the best possible person' to provide evidence as 'she is the one who actually orchestrated the interviews'.
He told the court: 'These were confidential sources who gave the interviews on condition of anonymity.'
He also said: 'The defendant, in its own coverage - going right back to the first article... that gave rise to this entire litigation - they themselves describe the interviews as anonymous.
'When they regaled their readers with a long and sensational article online within hours of the document being served upon them, they themselves described the interviews as anonymous and the names of the five friends as being put into a confidential court document. But, within hours, we find a volte face.'
Mr Rushbrooke QC then told the court that MailOnline published an article on July 1, the day after the confidential schedule containing her five friends' names was served on MailOnline's publisher Associated Newspapers Limited (ANL).
Mr Rushbrooke said the article was published just before 5pm, adding: 'If they got it at midnight, journalists were no doubt poring over it with glee in the morning.'
He said it was a 'massively long article which in its own sub-headline records, we say, accurately that ... 'Meghan has now identified the five friends, who spoke anonymously, naming them in confidential papers'.
Mr Rushbrooke said MailOnline published another article on Meghan's application shortly after the first one.
He said: 'Let there be no doubt about it, these two publications are what set off the chain reaction of other publicity given by other organs to the response. It could not possibly be suggested otherwise.'
Mr Rushbrooke added: 'It was the defendant and only the defendant because only the defendant had the document which started the wildfire.'
He continued: 'Other litigants do not make commercial fodder out of the other side's pleadings, but since this one does and since this one has asserted in correspondence that this very document is properly reportable by the media - although they graciously said they won't publish it until the outcome of today's hearing - that is precisely why we say an order ... is necessary'.
Mr Justice Warby said he will give his decision on the duchess's application in writing at a later date.
He said he was 'not going to make any predictions' as to when that would be, but that he would deliver his ruling as soon as he can.
In People's bombshell February 2019 interview, the five women, who were described by the magazine as 'a special sisterhood', lavished praise on Meghan.
One of them – identified in court papers by Meghan as 'Friend A' – told the world about the letter she had posted to her father in October 2018.
Thomas Markle said he spoke to Mail on Sunday afterwards - and shared the note - to 'defend himself' against an inaccurate portrayal of him in People.
Meghan named her five friends to the High Court in a confidential schedule which was kept secret. In a public document she named them as Friends A to E. They cannot be named
She identified Friend A as the one who had told People that the letter had said: 'Dad, I'm so heartbroken. I love you. I have one father. Please stop victimising me through the media so we can repair our relationship.'
Meghan claimed this was an 'unfortunately inaccurate' portrayal of her letter, stressing numerous times that she had known nothing of her closest friends' decision to go public.
She disclosed a list of those she had discussed the 'private' letter with in the papers lodged with the High Court - two of her friends, Prince Harry, her mother Doria Ragland, the press team at Kensington Palace (KP), and her solicitor.
Her lawyers told the High Court she had told 'some of her friends' about the fact she had sent a letter, adding that she had also 'discussed the contents of the letter with her husband, her mother, Friends A and C, the KP Communications Team and her solicitor'.
Meghan insisted more than a dozen times in last week's legal document that she had no prior knowledge of her friends' interview with People.
She added that she was so uninvolved in 'the process of the People article' that she only found out about it on the day it was published'.