Jersey accountant Robert Brown, 53, believes he could be the love child of Princess Margaret, who died in 2002 aged 71, and Group Captain Peter Townsend - who had an ill-fated romance with the Princess - making him 12th in line to the throne.

But his attempts to find out the contents of the Queen's sister's will and that of Queen Elizabeth the Queen Mother have so far been blocked by judges who say orders to seal the documents should remain in force.

Lord Chief Justice Lord Phillips and two other appeal judges said Mr Brown was entitled to a hearing of his claim to inspect the wills.

Lord Phillips, allowing his appeal, said: "It is unfortunate that the important issues to which we have drawn attention should be raised by an application made by a person motivated by a belief that is both irrational and scandalous."

Family Division President Sir Mark Potter struck out his claim in July last year that he had the right to examine the wills as vexatious and an abuse of process.

He said Mr Brown had no interest which had been adversely affected by the order of the former President, Dame Elizabeth Butler-Sloss, to have the wills sealed in 2002, a decision to which the Attorney General was party.

But in October, Lord Justice Thorpe, Lord Justice Dyson and Mr Justice Holman ruled in the Court of Appeal that it was at least arguable that Mr Brown had standing to assert a general public interest in whether it was right for them to be sealed.

Mr Brown returned to the appeal court last month to argue that point before the Lord Chief Justice, Lord Justice Thorpe and Lord Justice Dyson.

Geoffrey Robertson QC, representing Mr Brown, told the hearing: "This appeal raises important questions as to the circumstances in which wills, in particular those of members of the Royal Family, can be sealed and hidden from public inspection and the circumstances in which wills which have been sealed can be unsealed."