Jersey 'royal' claimant 'taking case to European court'
The accountant has been attempting to see the wills of the princess and the Queen Mother.
He said the European Court might help his long-term battle to determine his identity.
Mr Brown said women and illegitimate children did have the same rights as men when it came to royal succession and that he wanted the court to look at that.
Mr Brown was born on 5 January 1955 in Nairobi, Kenya, but his birth was not registered until 2 February.
The birth certificate gives the date he was born as 4 June 1955.
He also believes a mystery Privy Council meeting was held on the day he was born.
It was later that year Princess Margaret called off her wedding to Group Captain Townsend, a divorced father-of-two.
Mr Brown's parents are registered as Cynthia and Douglas Brown and he claims Cynthia Brown had been a model working for Hardy Amies, who was a favoured designer of the princess.
He has previously said years of research has led him to firmly believe the princess was forced to give up her "secret" son, but did visit him when he was young.
In a hearing in 2008, the Lord Chief Justice Lord Phillips said Mr Brown's beliefs were "irrational and scandalous" but his bid to inspect the royal wills has been backed by politicians in the UK.