Hi again, and thanks for your patience.
I think this may just be an Urban Legend, because the only thing I'm finding re: this subject, after researching TV dramas and newspaper headlines from that decade, is an elephant named Lilli who defecated on camera while on a children's show called 'Blue Peter'. Perhaps the newspaper was trying to attract readers by publishing that 'shocking' headline (if it was indeed, published), and it really referred to the animal, Lili.
I also found the following, from 'The Singing Detective', run on BBC in 1986, but it involved a male character defecating on the desk of a teacher, and it's not clear whether this was actually shown in the show. Scroll down about halfway, on this webpage, to 'The Singing Detective BBC, 1986' for a description.: http://cinetext.philo.at/magazine/voigts-virchow/suspense_potter_lynch.html
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