A Chinese businessman - described as a "close confidant" of Prince Andrew - has been barred from entering the UK over national security risks.
Known as H6, the man was invited to the royal's birthday party in 2020, and was told by Andrew's aide Dominic Hampshire that he could help in potential dealings with Chinese investors.
He was first excluded from entering the country in 2023 over national security fears by Suella Braverman, who was then home secretary.
In July that year, the Home Office said H6 was considered to have engaged in "covert and deceptive activity" on behalf of the Chinese Communist Party (CCP).
H6 argued it was unlawful and made an appeal to the Special Immigration Appeals Commission (SIAC).
Judges upheld the ban on H6 entering the country on Thursday, arguing the Duke of York could have been made "vulnerable" by his influence.
The specialist tribunal in London heard a March 2020 letter from Mr Hampshire - referencing the invitation to the duke's birthday - was found on H6's devices when he was stopped at a port in November 2021.
The adviser said in the letter: "I also hope that it is clear to you where you sit with my principal (Prince Andrew) and indeed his family.
"You should never underestimate the strength of that relationship… Outside of his closest internal confidants, you sit at the very top of a tree that many, many people would like to be on."
The 53-page ruling also referred to a 2021 document recovered from a device which listed talking points for a call between H6 and Andrew which said the prince "is in a desperate situation and will grab onto anything".
Judge Charles Bourne, Judge Stephen Smith and Sir Stewart Eldon said in their ruling that Ms Braverman "was entitled to conclude that his exclusion was justified and proportionate".
They noted that documents on his phone suggested H6 had "deliberately obscured his links" with the CCP and the United Front Work Department - a network of Chinese groups that operate abroad.
The judges added H6 had been able to generate relationships between prominent UK figures and senior Chinese officials, which could then be leveraged by the country's government.
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Mr Justice Bourne also said that H6 had "won a significant degree, one could say an unusual degree, of trust from a senior member of the Royal Family who was prepared to enter into business activities with him".
He added: "That occurred in a context where, as the contemporaneous documents record, the duke was under considerable pressure and could be expected to value (H6's) loyal support.
"It is obvious that the pressures on the duke could make him vulnerable to the misuse of that sort of influence."
(c) Sky News 2024: Prince Andrew's 'close confidant' barred from entering UK over national security fears