Kate Middleton should be called a "Queen Wag," according to a feminist author. Joan Smith called the Duchess of Cambridge an "unambitious," "machine-made" princess who has "done little" apart from marrying Prince William and falling pregnant.

Smith has devoted a chapter to the 31-year-old duchess in her new book "The Public Woman," in which she calls her "Queen Wag." Wag is a term used to refer to "wives and girlfriends" of prominent men, usually those who are in sports.

"By the age of 30, the new Duchess of Cambridge had done little since leaving university except play a supporting role to her boyfriend, marry him with great pomp and ceremony and get pregnant," she wrote in her book, according to the excepts obtained by The Daily Mail.

"She had never really enjoyed an independent identity or income - even her clothes were paid for by her father-in-law - and didn't seem to aspire to either.

"Unambitious, uncontroversial and bland, Kate Middleton was Queen Wag in everything but name."

She added that Kate has become famous "not for her achievements but her willingness to play the most traditional feminine role of all: waiting for a husband, getting married and not long afterwards becoming pregnant."

Smith didn't stop at Kate. She has also a few choice words for Princess Diana, Kate's late mum-in-law.

According to the excerpt acquired by The Province, Smith thinks Princess Diana "made catastrophic choices about men and showed not a glimmer of insight into why her relationships kept going wrong. Diana exemplifies a species of female narcissism which is repeatedly misread in popular culture, glamorising stunted ambition - wanting fame and admiration - and erasing any requirement for personal responsibility."

Smith's criticism of Kate and Diana comes just months after Booker Prize winner Hilary Mantel called Kate a "show-window mannequin with no personality of her own."

Kate is due to give birth to the future rule of the United Kingdom in July.