Parents of pupils at a prestigious London school have expressed outrage after discovering excerpts from the notorious "Sachsgate" tape is part of their children's GCSE course.
Transcripts of the lewd messages, including Russell Brand boasting of his "lovely sex" with burlesque dancer Georgina Baillie, were played to students at Hampstead School, Camden, as part of the school syllabus.
The messages originally left on Fawlty Towers actor Andrew Sachs's answer phone and broadcast live on BBC Radio 2 in 2008, detail Brand's affair with Sachs's granddaughter Baillie.
Brand boasts of his "lovely sex" with the Satanic Sluts dancer while Ross can be heard shouting "he f***ed your granddaughter" in the background.
Headmaster Jacques Szemalikowski defended the use of the tapes, saying they were no more vulgar than teaching Shakespeare.
"I think it is a totally appropriate thing to be doing. We are in the real world and children live in the real world.
"The unit is all about how people react to language and the limits of freedom of expression and this was a very famous snippet. It's all about interpretation."
Szemalikowski added pupils also studied the reaction on BBC's Newsnight and said there was a "lot of rude stuff" in Shakespeare too.
But Chris McGovern, chairman of the Campaign for Real Education, said the transcript was "completely unsuitable".
"I can't see any circumstances where it would be valid at GCSE level to be looking at that text.
"It was an appalling event and to give it the status of academic study is wrong."
The paper prompted a complaint from a parent, who said pupils originally thought the test paper, used for a mock GCSE exam, was a joke.
The comprehensive school in North London was awarded a gold star by Ofsted in 2001, and last year had the best GCSE results to date.