Grace of Monaco, about the American actress's marriage to Prince Rainier III, was met with laughter in the auditorium and eviscerated by the critics when it opened last year's Cannes Film Festival.
The Barfta judges took aim at a film - dubbed "Dis-Grace of Monaco" - where "a plucky woman fights to stop the super-rich having to pay their taxes. We almost miss Diana."
Last year, the biopic of Princess Diana swept the boards, winning worst film and worst actor for Naomi Watts in the lead role in what the organisers called a "misfire of biblical proportions".
Other recent royal flops include Madonna's WE, about Wallis Simpson and the abdication of Edward VIII.
Worst British film went to Pudsey the Dog: the Movie, which the judges described as a "train wreck," adding: "It's a film about a dog that danced on a TV show. God help us all."
David Walliams was shortlisted for worst actor for voicing the dog. Yet he was beaten by Simon Pegg, who starred in the "frankly creepy" Hector and the Search for Happiness. One voter described the Shaun of the Dead star as "the most puncheable lead in film history".
This year Cameron Diaz pulled off an extraordinary double. She was nominated for worst actress in Sex Tape - which made the judges "want to pour bleach in our eyes. And our ears" - and for worst supporting actress for her turn in Annie. That remake won worst US film for being so sickly sweet "watching it may well induce type two diabetes".
Special prizes included the Dick van Dyke award for calamitous accent awarded to Russell Crowe for his "frankly baffling accent in the frankly baffling" A New York Winter's Tale. The Fifa movie United Passions was also singled out for particular opprobrium.
Camilla Wright, founder of Popbitch, said the list of movies was so terrible that it makes "waterboarding seem like an attractive alternative".
The Barfta voting academy is made up of notable British film critics and industry professionals who vote anonymously. Popbitch has fronted the awards since they were set up in 2013.
- Independent