A Chinese businessman described as a “close confidante” of the Duke of York has lost an appeal over a decision to bar him from entering the UK on national security grounds.

The man, known only as H6, brought a case to the Special Immigration Appeals Commission (SIAC) after then-Home Secretary Suella Braverman said he should be excluded from the UK in March 2023.

Judges were told that in a briefing for the Home Secretary in July 2023, officials claimed H6 had been in a position to generate relationships between prominent UK figures and senior Chinese officials “that could be leveraged for political interference purposes”.

They also said that H6 had downplayed his relationship with the Chinese state, which combined with his relationship with Andrew, represented a threat to national security.

At a hearing in July, the specialist tribunal heard that the businessman was told by an adviser to Andrew that he could act on the duke’s behalf when dealing with potential investors in China, and that H6 had been invited to Andrew’s birthday party in 2020.

A letter referencing the birthday party from the adviser, Dominic Hampshire, was discovered on H6’s devices when he was stopped at a port in November 2021.

The letter also said: “I also hope that it is clear to you where you sit with my principal 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.”

In a ruling on Thursday, Mr Justice Bourne, Judge Stephen Smith and Sir Stewart Eldon, dismissed the challenge.

The judges said: “The Secretary of State was entitled to conclude that the applicant represented a risk to the national security of the United Kingdom, and that she was entitled to conclude that his exclusion was justified and proportionate.”

The Home Office confirmed in July 2023 that H6 would be excluded from the UK as he was considered to have engaged in “covert and deceptive activity” on behalf of the Chinese Communist Party (CCP) and that he likely posed a threat to national security.

The now-50-year-old former civil servant brought legal action for a review of the decision, arguing that it was unlawful.

The tribunal in London heard that H6 had said he avoids getting involved in politics, and only had limited links to the Chinese state.

His lawyers also argued that there was evidence that it was difficult for a Chinese national involved in business to avoid any contact with the CCP and that material related to his relationship with Andrew had to be read in the context of an advisor writing to someone who had been loyal to the duke in difficult times.

However Home Office lawyers argued that H6 had downplayed his links to an arm of the CCP, and that his relationship with Andrew could be used for political interference.

In their 53-page ruling, the judges said that Andrew could have been made “vulnerable” to the misuse of the influence H6 had.

They said: “The applicant 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.

“That occurred in a context where, as the contemporaneous documents record, the duke was under considerable pressure and could be expected to value the applicant’s loyal support.

“It is obvious that the pressures on the duke could make him vulnerable to the misuse of that sort of influence.

“That does not mean that the Home Secretary could be expected to exclude from the UK any Chinese businessman who formed a commercial relationship with the duke or with any other member of the Royal Family.”

The three judges said that H6 had enjoyed a private life in the UK, which had been described as the businessman’s “second home”, adding: “He has settled status, a home and extensive business interests in the United Kingdom. He was regarded as a close confidant of the duke.”

The judges continued the Home Secretary was “rationally entitled to decide” there was a potential to leverage the relationship, adding H6 was “not candid” about his links to the CCP.

They concluded: “In our judgment it was open to the SSHD to take a reasonably precautionary approach to the risk, and to take action rationally aimed at neutralising it so far as possible.

“Whilst excluding the applicant would not necessarily halt his activities, it would significantly hinder them.

“Cultivating relationships with prominent UK individuals would logically be much more difficult if no meetings could take place in the UK.”