A campaigner has called on BBC bosses to defend the “elitist” format of University Challenge in a public debate, after complaining that the show’s Oxbridge bias is even more pronounced in its Christmas specials. Frank Coffield, an emeritus professor of education, has asked for fairer entry rules that would confine Oxford and Cambridge to one team each in line with all the other universities. In a yearlong campaign, he has argued that the current format is rigged in favour of Oxbridge colleges, which he claims breaches BBC rules on impartiality. Now he has asked the BBC chief executive, Tim Davie, and the show’s presenter, Amol Rajan, who both attended Cambridge colleges, to a debate on the issues at Durham University, where Coffield used to teach. He has also raised the issue with the BBC chair-elect, Samir Shah, who studied for a PhD at St Catherine’s College, Oxford. In letters to Davie and Rajan, Coffield pointed out that the show’s Oxbridge bias was particularly apparent in its Christmas specials, where alumni compete on behalf of their former universities. He found that since the Christmas specials started in 2011, Oxbridge colleges have won nine of the 12 annual contests, and a quarter of the 168 teams that have taken part in Christmas contests have been Oxford or Cambridge colleges. Coffield has urged the BBC to disclose the full details of all the entrants in the 61-year history of a show that ran on ITV from 1962 to 1987 before switching to the BBC in 1994. He said the requests had been repeatedly declined. In his letters to Davie and Rajan, he wrote: “What was the BBC so determined to conceal? The fact that it continues to rig this quiz in favour of the already privileged. The senior executives in charge of the show ignore criticisms and continue to push their unjustifiable favouritism of the Oxbridge colleges they themselves attended.” He said the alleged bias was “symptomatic of how this country is run – in the interests of a small elite who fight to preserve their unearned advantages for their colleges and their children”. Challenging Davie and Rajan, he asked: “Why do you allow this programme to tarnish the BBC’s reputation for impartiality? Is it because you are part of the elite, using your position to perpetuate these privileges?” Coffield said the over-representation of Oxbridge colleges in the Christmas specials “clearly breaches the BBC’s Royal Charter which stipulates impartiality”. In his letter to Rajan, he said: “I wrote to you three times when you first became the new presenter of this quiz to alert you to its failings, but you didn’t reply to any of my emails, presumably because you support the format. I therefore challenge you to a public debate on this scandal.” Coffield’s suggested venue for the debate is Durham University, which won the competition last year, and which is confined to one team only despite having an Oxbridge-style college system. Davie, Rajan and Shah have yet to respond. His messages were passed to the BBC complaints department, which said in an email response: “As we have stated previously, all institutions that deliver higher education courses at the level of Bachelor’s degree or equivalent or higher are welcome to apply to take part on University Challenge. There are also currently around 230 further and higher education colleges in the UK without degree-awarding powers that nevertheless deliver university-level courses.” In reply, Coffield asked: “If there are 230 institutions eligible to apply, how come between 30% and 40% of teams come from Oxbridge colleges?” A BBC spokesperson comments: “We totally reject this – over the last 12 years the University Challenge Alumni series has set out to reflect the UK’s graduate population and has represented a wide range of universities in each series.” Earlier this month, the BBC was forced to pull one of its Christmas special episodes after complaints about a lack of provision for contestants with disabilities. In the episode, which was filmed in November, two Oxford and Cambridge colleges were competing against each other. The rest of the festive series is not affected by the decision to pull the episode. Fourteen teams entered seven first-round matches of Christmas University Challenge, which will be broadcast from Monday evening.