In an interview with Fox News, Mr Bullen listed some of the similarities between Harry and Edward.
Edward, who abdicated in 1936 to marry an American divorcee and socialite Wallis, wrote a ghost autobiography after being cut with no source of income.
The book A King’s Story: Memoirs of the Duke of Windsor was published in 1951 and included details of the royal split and its relationship with Wallis. Harry is currently writing his own memoir after signing a £ 29million four pound mega-deal.
The first book, which is yet to be titled, will include “the definitive account of the experiences, adventures, losses and life lessons that helped shape it,” Random House announced.
The pair married divorced American women, experienced “sibling rivalry” and gave explosive interviews about their lives with the royal family.
“It’s fascinating to draw the parallel between the two,” said Mr. Bullen. Both married divorced American women. We all know it, but it goes much further than that.
“Edward and his brother also experienced their own sibling rivalry which can be compared to Harry’s strained relationship with his brother, Prince William. ”