Crisis talks have begun in earnest to determine the specific terms of a potential deal, which the Duke would want to be signed off before his deposition, tentatively scheduled for next month.

Mr Boies has indicated that a public apology would have to form the plank of any agreement, but for the Duke, who has denied the claims, any acceptance of liability is off the table.

Although he is now defending the case as a “private citizen”, the monarch would have to sanction such a significant legal move. 

A public statement would likely point to the global publicity the case had generated and the ensuing negative effect on the institution.

Who is Robert Olney?

Mr Olney, the Duke’s former equerry, will be called to give evidence in his sexual abuse case, it emerged last night.

Lawyers for Ms Giuffre, also plan to question Shukri Walker, who claims to have seen the Duke in Tramp nightclub in London on the night he is alleged to have forced Ms Giuffre to have sex with him.

“Because Prince Andrew has denied ever meeting plaintiff or being at Tramp Nightclub during the relevant time period, Ms Walker’s testimony is highly relevant,” they wrote in court documents.

A formal request to interview the two British witnesses has been made via letters rogatory, the method of requesting assistance between countries during legal proceedings.

New York federal court judge Lewis Kaplan will now formally ask British authorities for assistance in obtaining their testimony.

An online profile for Mr Olney, from Marlow, Bucks, suggests that he was employed as the Duke’s equerry from 2002 until 2004. But according to a handful of appearances in the Court Circular, he was still representing the Duke at official events in 2011.

The Army veteran is now head of Safety and Business Delivery at Civil Aviation Authority, according to his LinkedIn profile.