The British actress wrote the screenplay for a reboot of the 1964 musical which starred Audrey Hepburn as Eliza Doolittle, but the project was hit with numerous delays.
Keira Knightley and Carey Mulligan were both linked to the lead role, but rumoured director Danny Boyle reportedly dropped out and production never got off the ground.
Thompson rewrote the script a number of times, but now admits the movie may never make it to the big screen, telling Britain's Daily Mail newspaper, "I did a new version of My Fair Lady, which they're not making."
A source adds to the publication, "They ended up with a director, John Madden, but they couldn't find the right Eliza Doolittle, and there were also complex rights issues at play."
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