The only reason Charles married Diana

The book also claims that during their rows, Diana would taunt Charles by saying he'd "never be king" (Getty)
The book also claims that during their rows, Diana would taunt Charles by saying he'd "never be king" (Getty)

A new Prince Charles biography claims the only reason he proposed to the late Princess Diana was because his father told him to. 

New York Times best-selling author Nancy Bedell Smith claims that Prince Philip pushed his son into marrying Diana by writing him a note, saying his indecision about his partner threatened her reputation. 

Prince Charles: The Passions and Paradoxes of an Improbable Life is said to be an unflattering portrayal of the 68-year-old royal and his ill-fated marriage, claiming he and his staff "dealt with Diana's bewildering and often infuriating behaviour by placating her, trying to distract her and, ultimately, out of frustration, abandoning her".

Bedell Smith also claims Camilla, who Prince Charles is currently married to, was always the love of his life - but her confidence and "enormous sex appeal" meant she wasn't virginal enough to step into the royal role. 

The biography claims the marital problems between Di and Charles were extensive, and says some of the issues stemmed from their 12-year age gap. It is also believed that during their rows, Diana taunted Charles that he would "never be king," knowing the heartache that caused the throne's next-in-line. 

The book will be released on April 4. 

Newshub.