Madonna refused to buy letters written by Wallis Simpson as she researched her new movie W.E. - and simply memorised their content instead.
The Material Girl makes her directorial debut in the period piece, which is based on the romance between British monarch King Edward Viii and American divorcee Wallis Simpson, whose relationship forced the royal to abdicate the throne in 1936.
Madonna studied various scripts and notes while writing the movie - but she refused to pay for the historical musings.
She tells Britain's Glamour magazine, "I'm sure I've read every book on the Duchess of Windsor. And once people knew I was doing research and writing the script they wanted to sell me their letters.
"I didn't purchase any, but I read them, noted the information and then said thanks, but no thanks. I watched every documentary ever made, and stayed at the house in the south of France that they lived in during the war - it's now owned by (Russian businessman) Roman Abramovich. I tried to go to places that they were at and soak up their energy. Of course, I wasn't allowed in Windsor Castle."