The judge’s latest ruling follows a two-day case management hearing in May, during which Antony White KC, for Associated Newspapers, asked the court to order the claimants to “search for and disclose any documents that relate to payments, royalties or inducements paid, provided or offered, or any demands or threats made, in order to obtain documents, information or other co-operation”.

The barrister said a limited number of documents had been disclosed, which showed that “payments were made or offered” to “procure evidence and invoices”.

Mr Justice Nicklin said he was satisfied that any documents suggesting witnesses had been paid or offered other inducements should be disclosed.

“That is because there is a real prospect that Associated will be able to rely upon this evidence to attack the credibility of such witnesses,” he added.

“Ultimately, the issue of whether the payment or inducement does affect the credibility of any witness is a matter to be resolved at trial. In this case, the stance adopted by the claimants has been undermined by their inconsistent and incoherent approach to disclosure of documents relating to payments to potential witnesses and/or other inducements.”

The claimants were also ordered to conduct further searches for evidence relating to what has been described in court as their “personal watershed moment” – when they became aware that they had a potential claim.

The Duke of Sussex is said to have sent a text message to Baroness Lawrence alerting her that “information” had come to light “that she would want to know about”, prompting her to join the legal action just a few months later.

In a subsequent email sent by the Duke to Baroness Lawrence about the material his barrister, David Sherborne, had “come across”, he said “he and one of his team would be keen to come and speak to you… in order to explain what this material shows and what your options are”.

The Duke was told he had a potential claim by Mr Sherborne, to whom he was introduced by Sir Elton while on holiday at the singer’s home in France.

Associated Newspapers had sought information about such “moments”, including details of who had allegedly provided what information to whom and on what dates.

‘Surprising’ lack of documentation

Mr Justice Nicklin said he found the lack of documentation on these pivotal moments “surprising”.

Such revelations would surely have prompted “communications between trusted friends and family members; messages seeking advice or guidance, or expressing shock or outrage”, he said.

The judge noted that a “complete absence of corroborating documents” may be used to suggest these moments were not “quite as shocking” as claimed.

Meanwhile, the claimants’ attempt to access broader call data and other information was refused by the judge, who described the requests as “disproportionate or unfocused”.

Broad allegations made about the alleged use of unlawful information gathering across all Mail titles over 25 years were also rejected.

Mr Justice Nicklin warned that such allegations could not prove individual claims and that the court would “tightly manage” the scope of the generic case to prevent the litigation from becoming “a wide-ranging public inquiry”.