Prince Philip’s will is to remain secret for 90 years to protect the “dignity” of the Queen.

The High Court ruled that the Duke of Edinburgh’s will is to remain sealed because of the Queen’s constitutional role.

Philip – the nation’s longest-serving consort – died aged 99 on April 9, just two months before he would have turned 100.

After the death of a senior member of the royal family, it has been convention for over a century that an application to seal their will is made to the President of the Family Division of the High Court.

Your Local Guardian: Prince Philip

This means the wills of senior members of the royal family are not open to public inspection in the way a will would ordinarily be.

The current president, Sir Andrew McFarlane, heard legal argument from lawyers representing Philip’s estate and the Attorney General – who represents the public interest in such matters – at a private hearing in July.

Why will Prince Philip’s will remain sealed?

In a ruling published on Thursday, Sir Andrew ordered that Philip’s will is to remain sealed for 90 years from the grant of probate – the formal process which confirms the authority of an executor to administer a deceased person’s estate – and may only be opened in private even after that date.

The judge said: “I have held that, because of the constitutional position of the Sovereign, it is appropriate to have a special practice in relation to royal wills.

“There is a need to enhance the protection afforded to truly private aspects of the lives of this limited group of individuals in order to maintain the dignity of the Sovereign and close members of her family.”

He said the ruling was to make as much detail as possible public without “compromising the conventional privacy afforded to communications from the Sovereign”.

Your Local Guardian: Prince Philip leaves King Edward VII Hospital in London

The judge said it was in the public interest for him to make clear he had neither seen, nor been told anything of the contents of, Philip’s will, other than the date of its execution and the identity of the appointed executor.

Sir Andrew said he had decided to hold the earlier hearing in private because a series of announcements, hearings and then a judgment would have been likely to “generate very significant publicity and conjecture”.

He concluded this would be “entirely contrary to the need to preserve the dignity of the Sovereign and protect the privacy surrounding genuinely private matters”.

He added: “The publicity would, therefore, in part, defeat the core purpose of the application.”

Is a Royal will in the public interest?

The judge said: “I accepted the submission that, whilst there may be public curiosity as to the private arrangements that a member of the royal family may choose to make in their will, there is no true public interest in the public knowing this wholly private information.

Your Local Guardian: Prince Philip

“The media interest in this respect is commercial. The degree of publicity that publication would be likely to attract would be very extensive and wholly contrary to the aim of maintaining the dignity of the Sovereign.”

Sir Andrew said that, as the Attorney General was there to represent the public interest at the hearing, there was no legal reason for any further representations by media organisations.

Are Royal Family wills always kept secret?

Lawyers representing Philip’s estate had argued at the private hearing that news of that hearing and the application “might generate wholly unfounded conjecture” which would be “deeply intrusive” to the Queen and royal family.

Outlining the history of previous similar decisions, Sir Andrew said the first member of the royal family whose will was sealed on the direction of the court’s president was Prince Francis of Teck.

He was the younger brother of Queen Mary and, following his death in 1910, an application for his will to be sealed and not published was granted.

Sir Andrew said that, as President of the Family Division of the High Court, he is custodian of a safe which holds 30 envelopes – each containing the sealed will of a deceased member of the royal family.

Your Local Guardian: Queen Elizabeth II and Prince Philip

He said the earliest envelope is labelled as containing the will of Prince Francis of Teck, and the most recent additions are the wills of the late Queen Mother and Princess Margaret, the Queen’s sister.

In 2007, Sir Mark Potter, then president of the family division, dismissed an application by Robert Andrew Brown for the unsealing of the wills of the Queen Mother and Princess Margaret.

Mr Brown claimed to be the illegitimate child of Princess Margaret and asserted that he had an interest in unsealing and inspecting the wills in order to establish that claim.

However, his claim was not accepted by the court and was struck out as “vexatious and an abuse of process” – a decision upheld by the Court of Appeal.

Sir Andrew said the position has now changed following his judgment in respect of royal wills being sealed indefinitely and that, 90 years after the grant of probate, an “initial and private process will be undertaken to consider whether at that stage the will may be unsealed and made public”.

He said the private process would involve inspection by the monarch’s private solicitor, the Keeper of the Royal Archives, the Attorney General, and by any of the deceased’s personal representatives who may be available.

The physical process of unsealing must be conducted by a professional archivist to ensure that the document and its seals are properly preserved.

Sir Andrew said any future judgments on applications to seal royal wills would remain closed, and therefore will not be made public.

The judge said he wishes to publish an annex to his judgment detailing the names on the 30 envelopes in the safe, but will not do so at present in case his decision to do so is the subject of a legal challenge.