editor Nick Robinson, Thea Rogers, Andrew Neil, Neil's editor Robbie Gibb and Kamal Ahmed. A study by Cardiff University academics, which was funded by the BBC Trust, was published in August 2013 and examined the BBC's coverage of a broad range of issues. One of the findings was the dominance of party political sources; in coverage of immigration, the EU and religion, they accounted for 49.4% of all source appearances in 2007 and 54.8% in 2012. The data also showed that the Conservative Party received significantly more airtime than the Labour Party. In 2012, Conservative leader and then Prime Minister David Cameron outnumbered Labour leader Ed Miliband in appearances by a factor of nearly four to one (53 to 15), and governing Conservative cabinet members and ministers outnumbered their Labour counterparts by more than four to one (67 to 15). A former Director General of the BBC, Greg Dyke, criticised the BBC as part of a "Westminster conspiracy" to maintain the British political system. Before to the 2019 general election, the BBC was criticised for biased coverage that favoured the ruling Conservative Party. For instance, issue was taken with a clip used from a BBC Question Time leader's special episode in which the part showing audience laughter at Prime Minister Boris Johnson's response to a certain question was edited out. BBC officials addressed the issue and admitted their mistake. Furthermore, the BBC was accused of subjecting Jeremy Corbyn and Jo Swinson to a gruelling interview by Andrew Neil but not requiring Johnson to go through the same and of arranging it beforehand. The Guardian columnist Owen Jones also took issue with the BBC rescinding its policy of not letting Johnson be interviewed by Marr unless he went through one with Neil. The BBC defended its decision to waive the requirement by citing national interest amidst a terror attack in London on 29 November 2019. Some commentators, such as Peter Oborne, have argued that there is a culture of "client journalism" which has flourished in recent years due to a closeness between the BBC and the ruling Conservative Party, which has led to their bias in favour of the establishment. For example, from 2008 to 2017, Robbie Gibb was head of the BBC Westminster and therefore in charge of the BBC's political programming. His brother, Nick Gibb, is a Conservative MP and Minister for Schools, and Robbie Gibb took a job