A man claiming to be the love child of Britain's Princess Margaret will take his claim to London's High Court on Tuesday.

Robert Brown - a 52-year-old accountant from Jersey - insists he was born following an affair between the late princess and a man she was once in love with, Group Captain Peter Townsend, making him Queen Elizabeth's illegitimate nephew.

Brown told Britain's Daily Mail newspaper: "It's going to be an extremely hard day for me and it will be harder if it is heard in open court. But justice should be seen to be done in the open. The belief I have is an honest one."

Despite inconsistencies in his story, he has secured a lawyer from David Price, one of the most respected media law firms in the country.

He is attempting to gain access to the last will and testament of both Britain's Queen Mother and Princess Margaret. Brown believes their wills may contain evidence to support his claim.

His only evidence so far appears to be a memory of meeting the princess when he was a child and comments referring to his legitimacy made by relatives.

Brown was born in Kenya on January 5, 1955, and is convinced Margaret was his mother despite the fact that she was in Norfolk, not Nairobi, at the time of his birth.

He believes he was adopted and both his parents, society model Cynthia Brown and his father Douglas, who was posted to Kenya with the Army, are now dead, as are the princess and Group Capt Townsend.

Brown has called Margaret's biographer Noel Botham as a witness. Botham does not necessarily believe Brown's claim, but does strongly believe royal wills should be open to public scrutiny.

Brown wants his case to heard in an open court but royal lawyers will on Tuesday submit a strike application for the case to be heard in closed chambers.