A former Goldman Sachs banker has advanced closer to calling Andrew Mountbatten-Windsor as a witness in a high-value civil fraud trial scheduled for next month in London. The High Court ruled on Thursday that Selman Turk may rely on a late witness summary related to Mountbatten-Windsor, thereby allowing Turk to seek evidence from the former prince during the proceedings.

The case involves a £40 million claim brought by Nebahat Evyap İşbilen, a Turkish businesswoman who relocated to the United Kingdom after her husband, a politician, was imprisoned in Turkey. İşbilen alleges that Turk misappropriated approximately $90 million in assets she entrusted to him, diverting around £40 million into offshore accounts and companies under his control. Turk denies the allegations, asserting that all fund transfers were authorised and intended to protect İşbilen’s wealth, and maintains he has provided a full accounting of her assets.

Mountbatten-Windsor emerged in the litigation after disclosures revealed that significant sums connected to İşbilen reached the former prince’s household. Turk’s legal team argued that evidence from Mountbatten-Windsor is vital, describing it as a “central pillar” in challenging the credibility of İşbilen’s claims. They characterized the former prince’s testimony as “highly relevant and highly probative.” Conversely, İşbilen’s lawyers contended that Mountbatten-Windsor’s testimony would largely be irrelevant to the trial and could cause undue disruption. They also noted that Mountbatten-Windsor had reached a settlement with İşbilen, leaving no outstanding claims against him.

Mr Justice Adam Johnson, presiding over the case, determined that it would be unfair to exclude the possibility of Mountbatten-Windsor giving evidence, thereby clearing the way for Turk to formally request the court to issue a witness summons. Should a summons be issued and served, Mountbatten-Windsor would have the right to contest it.

Mountbatten-Windsor, who was stripped of his royal titles by King Charles in October of last year, has not commented on the ruling, and a representative did not respond to requests for statement. Turk’s legal representatives expressed satisfaction with the court’s decision, emphasizing the importance of presenting a comprehensive evidential record.

The trial is set to begin next month, with the outcome expected to hinge partly on the evidence linked to Mountbatten-Windsor’s involvement.