London, Aug. 27: Eton College, possibly the most famous public school in the world which has produced 19 Prime Ministers, is finding itself at the centre of a cheating scandal that has led to the exit of its Pakistani-origin deputy headmaster.

The sacking of Mo Tanweer, who passed on intelligence on exam questions, implies a setback for Eton's experiment with ethnic diversity.

The boarding school, which was founded in 1440 by Henry VI and now charges £37,000 a year in fees, has not had too many non-white teachers in what has become a multicultural Britain. It has a fair number of Indian boys.

The story that has emerged from Eton is a little complicated but arises from the fact that the school uses pre-university exam papers set by a board called Cambridge International Examinations (CIE).

The temptation for Tanweer was that he was himself an examiner for the CIE and drew up the exam papers. He emailed some of the teachers in his economics department at Eton with information about practice papers, which meant that the boys were deemed to have an unfair advantage.

Before any big exam, students work on "practice papers". Tanweer sent some through to the teachers in the economics department so that pupils could work on them.

The practice papers bore a startling resemblance to the actual exam questions - which Tanweer had either set himself or to which he was privy in his capacity as a CIE examiner.

It was considered that the Eton boys, unwittingly, had an advantage that pupils in other schools did not have. In fact, it was felt that Tanweer had engaged in cheating.

Tanweer, who lives in Berkshire with his partner Emily and three-year-old son, could not be reached.

Why would anyone undertake such a risky course of action when Eton boys are so well taught that they routinely get the top marks anyway? No clear answers were available but some suggested that the "prestige" of the teachers shoot up if the students perform spectacularly.

However, the scandal has ensured the departure of Tanweer, whose name, when the time came, might have figured in the frame as Eton's first Asian-origin headmaster.

The upshot is that the headmaster has had to write to the boys and their parents informing them that Tanweer has left the school - a euphemism for sacking. To the distress of the boys, their marks from the section of the economics paper which was compromised has been "rescinded" and their overall result taken only from the untainted portion of the exam papers.

The universities have also been informed that whatever happened was not the fault of the boys. Whether this will damage the boys' prospects remains to be seen - a difference of a grade can make all the difference between acceptance and rejection for a much sought after place at a top university.

Simon Henderson, Eton's headmaster, told parents and pupils in a letter: "I am very sorry to be writing with this extremely unwelcome news. Regrettably this decision has had to be taken by the examination board because of the actions of a member of Eton's staff.

"This is a matter that, as headmaster, I have taken very seriously and Mr Tanweer has now left Eton's employment."

"There is no suggestion that any boy at Eton has done anything wrong, nor is any member of staff at Eton other than Mr Tanweer implicated. However, CIE has decided that they cannot accept the marks of any candidate at Eton for this paper because to do so would threaten the integrity of the exam and certification."

Henderson said Eton would be writing to all UK universities that its candidates had applied to, "to make very clear that the candidates are not to blame in any way".

Tanweer, who was born in Pakistan, had moved to England and enrolled at Aylesbury Grammar School in the 1990s.

Tanweer was considered a high-flyer. He joined Eton in 2015 as an economics teacher, became head of the department and was swiftly promoted to a senior post as a deputy head last year.

According to an online profile, Tanweer graduated in economics in 2004 from St Catharine's College, Cambridge (where Amitabh Bachchan's father, the poet Harivansh Rai Srivastava alias Bachchan, had done a PhD on Y.B. Yeats and the occult and mysticism in the 1950s).

Tanweer later worked as an investment banker. By 2006, he had started teaching economics at Merchant Taylors' school in Northwood, Hertfordshire, where a high proportion of the boys are Gujarati. Between 2010 and 2015 he was head of economics at Oundle School in Northamptonshire, another boarding establishment.

An Eton College statement confirmed yesterday: "Eton College can confirm that following an investigation by the Cambridge International Examinations Board into maladministration, the board concluded that there had been a breach of exam security by one of Eton's teachers in relation to one of the Pre-U Economics papers.

"Eton took this matter extremely seriously and co-operated fully with CIE's investigation throughout.

"The teacher concerned has left the school. Whilst pupils had done nothing wrong, they were inadvertent recipients of confidential information and so the board awarded them assessed marks for that paper according to its established method. Eton College deeply regrets that this incident occurred."