The claims emerge in a new production about Harry's mum Princess Diana called Truth, Lies, Diana
Prince Harry will be laughing off the latest effort to reignite rumours that ex-Army officer James Hewitt is his real dad.
The claims emerge in a new play about Harry's mum Princess Diana called Truth, Lies, Diana.
Writer Jon Conway claims to have won approval from Hewitt, 56, who has described the scenes about his life with the tragic royal as "accurate".
The former Household Cavalry officer's backing is an apparent U-turn as he has previously denied claims Prince Charles is not Harry's father.
Mr Conway says his production aims to shed new light on the truth about Diana, killed in a car crash in 1997, and expose secrets the establishment has kept hidden.
The Royal household has never officially commented on the paternity claims but Harry was reassured long ago the conspiracy theories about his parentage are false.
The 30-year-old prince, born in September 1984, is so relaxed about the speculation that he has even appeared to joke about it.
During a visit to Bacon's College in South East London with William and Kate in July 2012, a young boy shouted across the football field to Wills: "Are you two brothers?" Quick-witted Harry instantly replied: "We're not sure."
Mr Conway, who wrote the 2010 musical All The Fun Of The Fair which starred David Essex, claimed his new work is the result of "meticulous forensic research" including "revelations from previously silent sources".
He said: "There is a startling revelation that James Hewitt makes and he has allowed me to make it in the play.
"This is the fact that his relationship with Diana started 18 months before Prince Harry was born.
"We're not saying he is Prince Harry's father although the audience may take their own view on that."
Hewitt confirmed he knows Mr Conway but has refused to be drawn on the play's contents saying: "I am sure it is accurate."
But royal experts have poured cold water on the claims.
Penny Junor, who has just published an acclaimed biography of Prince Harry, said: "I've spoken to people around at the time and they all say that James Hewitt wasn't in the picture before 1986. Diana didn't hide Hewitt when the relationship began. She kept him in plain sight."
Respected royal author Margaret Holder said Hewitt was trying to raise his profile.
She said: "I think this will put him back in the spotlight and it tells producers of reality TV programmes, 'Hello, I'm here'.
"It's a nonsense but it's all a game." Biographer Hugo Vickers said: "If you talk to certain people you will get a version of events these people are keen to peddle. They have an agenda of their own."
The play, which opens at London's Charing Cross Theatre on January 9, follows a journalist trying to uncover the truth about Diana's death.
