Panorama's star reporter Tom Mangold is astonished that inquiry into Martin Bashir won't investigate a 'cover-up' at BBC after the Diana interview

Tom Mangold was a leading light of Panorama at the time of the world scoop

A distinguished veteran BBC reporter has expressed his astonishment that the inquiry into Martin Bashir will not investigate a 'cover-up' at the Corporation after the 1995 interview with Princess Diana.

Tom Mangold – who was a leading light of Panorama at the time of the world scoop – has also challenged the probe led by former Master of the Rolls Lord Dyson to answer five crucial questions.

Last night he told the Mail: 'I am somewhat baffled by the complete absence of any reference in Lord Dyson's brief to investigating the events within the BBC after the story of the forgeries broke.'

Mr Mangold, who was a reporter on Panorama for 26 years, has previously spoken about his conviction that executives on the programme 'conspired, lied, deceived and cheated' to hush up the scandal, adding: 'The true story is much bigger than Bashir.'

The BBC has been forced to launch an investigation into claims that Martin Bashir told a string of lies to secure his bombshell Panorama interview with the princess Diana in 1995  

Last night he said: 'I know there was a cover-up to blame 'jealous colleagues, trouble makers and leakers' on Panorama – people who simply didn't exist. I know. I was there.'

Martin Bashir

He also outlined the points he believes Lord Dyson must address in investigating the use of faked bank statements and other ruses which led to Diana agreeing to the world exclusive interview.

He suggested the questions should be: '1. What steps did the BBC and, in particular, Martin Bashir take with a view to obtaining the Panorama interview in 1995?

'2. Were those steps appropriate, particularly in regard to the BBC's editorial standards at the time?

'3. To what extent did the actions of the BBC and, in particular, Martin Bashir influence Diana's decision to give an interview?

'4. What knowledge did the BBC have in 1995 and 1996 of the relevant evidence, such as the forged bank statements?

'5. How effectively did the BBC investigate the circumstances leading to the interview?'

Mr Mangold, 86, specialised in investigative stories and worked on more than 100 Panorama documentaries.

He won the Royal Television Society's current affairs prize.