Why did TV journalist David Mills, the producer of a Panorama film on the McCann affair, quit the project before it was transmitted last week? The Observer's David Rose reveals the inside story of the latest row to hit the BBC's flagship show

In the credits at the end of last week's Panorama special on the disappearance of Madeleine McCann, one name was conspicuous by its absence - that of David Mills, the programme's original producer. His name had disappeared from the end credits despite the fact that it was his company, Mills Productions, that had done all the research and was responsible for bringing the exclusive footage at the film's heart to the BBC.

Two weeks before transmission last Tuesday, Mills - one of Britain's most respected documentary-makers, who in his 40-year career has made 120 investigative films for broadcasters including the BBC, Granada, Thames and America's CBS - walked out of the programme after a furious row with Panorama's editor, Sandy Smith, over the programme's approach and argument.

He then wrote a stinging email to the BBC attacking Panorama for losing its journalistic passion. It has created a stir in the media world, mixing as it does the controversial issues of the McCanns and how their story is covered, journalistic balance and television current affairs.

'I had written a draft script and had already been told it was compelling,' Mills said. 'Sandy turned up with a completely different version and basically imposed it on me. I told him, "I cannot edit the film to this: it's a completely different show, and I'm not going to do it." To have this happening is very depressing.'

The incident - one of several controversies Panorama has faced this year - suggests, Mills said, that 'the BBC is no longer interested in serious current affairs'. BBC sources confirmed last night that the decisions about the programme's shape had been taken 'close to the top' of the BBC management hierarchy - which has already conducted a series of internal meetings over how the corporation should approach McCann case coverage in general.

As one of those interviewed by Mills and the programme's reporter, Richard Bilton, I can attest to how different the programme shown was to what they told me less than a month ago that they were envisaging. Along with The Observer's Ned Temko, who has covered the case for this newspaper, I ended up on the cutting-room floor. At that stage - as Mills's draft script makes plain - his intention was to make an analytical, investigative programme that would have been very critical of the Portuguese police, not only for the errors in their investigation, but for their apparent campaign of disinformation designed to put pressure on Madeleine's parents, Kate and Gerry McCann. It would also have criticised both the local and British press over allegations that they recycled unfounded rumours with little sign of fact-checking or detachment.

It would, as Mills confirmed again yesterday, have scrutinised the various allegations that have been floated against the McCanns and concluded they are baseless: 'We had an investigative team looking into the story for weeks. Our assessment was that the purported DNA evidence was weak and inconclusive, while so far as we could tell the supposedly significant "discrepancies" between the stories told by the McCanns' friends about the night of Madeleine's disappearance amount to very little indeed.'

The original film would have compared Madeleine to the JonBenet Ramsey case in Colorado, about which Mills has made three previous documentaries. After the body of JonBenet, a child beauty pageant winner aged six, was found in her parents' Boulder home, they were vilified by the police and media, despite their continued insistence that they had nothing to do with her death. They claimed she had been killed by an intruder. Mills's version of the McCann Panorama featured an interview - eventually not used - with JonBenet's father, John, in which he said that the Colorado police 'did a great job of convincing the media and the world that we were guilty, but they couldn't charge us, because of course they had no case'. Years later DNA evidence proved beyond doubt that JonBenet had been killed by an intruder. John Ramsey told Panorama: 'It's a life-time damage. No question about it.'

The programme on the McCanns that was broadcast by Panorama was much less ambitious. It recited the case both for and against the McCanns, but had nothing harsh to say about either the police or the media. It did include new material, including a video diary shot of the McCanns in Portugal by their friend John Corner - footage that had been acquired by Mills and had led to his company getting the BBC commission.

It also cast doubt on some of the wilder claims published by the tabloids, and contained the first interview with Jane Tanner, one of the McCanns' companions on the holiday in Praia de Luz last May, who said that she was certain she had seen a girl who looked like Madeleine being carried in the street by a strange man around the time she is thought to have disappeared. But the programme avoided firm conclusions.

Having handed the film's editing over to a colleague, Mills emailed Smith on Monday, the day before transmission, saying he felt compelled to remove both his name and his company's from the credits. 'In part this is because its muddled structure and lack of narrative drive means it is far below the standard of any work that I or my company would wish to be associated with,' the email said. 'In part, too, my decision reflects the programme's intellectual impoverishment. The McCann case poses issues of real importance which Panorama should have examined. That it is instead running a laboured, pedestrian, extended news report is shameful.

'But the most important reason for my decision is that because the programme is insufficiently analytical it verges on the dishonest. Our lengthy investigation revealed that there is no meaningful evidence against the McCanns... The real question must be how, without any meaningful evidence, the Portuguese police and the media in Portugal and Britain have been able to convince most people that the couple were involved.'

Mills had been working closely with a CBS team, which also used the video diary footage. They, he told Smith, had concluded it was 'ludicrous' and 'crazy' to think the McCanns could have caused the death or disappearance.

Smith emailed Mills back, accusing him of wanting to broadcast 'advocate journalism', and pointing out that the broadcast version did describe some of the allegations against the McCanns as 'tenuous, to put it mildly'. Smith said that, while it was true that the programme 'changed substantively,' this was because 'it is a current affairs programme and it was overtaken by events'. He added: 'To get Jane Tanner and some of the McCann family meant that some of the other stuff moved to the edge, and the original version was just not journalistically as important.'

Mills disagrees. 'So far as I can see, investigative journalism at the BBC is over,' he said. 'The broadcast script contains nuances that suggest that the McCanns still have a case to answer. The BBC should have had the courage to state that this is simply not so.'

Clarence Mitchell, the former BBC reporter who is the McCanns' spokesman, said Kate and Gerry were 'content' with the broadcast version and accepted that events meant it had to change. He said they had spoken to Bilton and told him they considered the film to be 'fair'.

Other McCann family members were less happy. John, Gerry's brother, whose interview was broadcast, said: 'It wasn't the programme that I was told they were going to make. They've made something very different, and I am disappointed, because I'd hoped the full story was going to be told. Nevertheless I'm pleased they interviewed Jane Tanner. She said she saw Madeleine being abducted, and we want people to remember that.'

The row follows controversies over previous films this year, such as a report on Scientology by former Observer journalist John Sweeney, in which he lost his temper and turned - in his words - into an 'exploding tomato,' and a story claiming that wi-fi technology might be harmful, which was denounced by some scientists as 'irresponsible'.

As someone who once spent a year reporting for Panorama myself, I know that no BBC programme is more closely scrutinised and, sometimes, fought over. The fact remains some of its most distinguished contributors, including Tom Mangold and John Ware, have left in recent years, and that it has been repeatedly accused of punching below its weight. Mills is not a marginal figure, and the CBS film with which he was collaborating was much firmer in its conclusion that the McCanns had to be innocent.

Last night the BBC hierarchy was closing ranks to resist Mills's arguments. Outside the corporation, they may not be as easily dismissed.

'Your programme verges on the dishonest'

From: David

Sent: 19 November, 2007 12:12

To: 'Sandy Smith'

Subject: credit

Dear Sandy,

As you know, in the end I felt I could not leave either my name or my company credit on the programme.

In part this is because its muddled structure and lack of narrative drive means it is far below the standard of any work that I or my company would wish to be associated with.

In part, too, my decision reflects the programme's intellectual impoverishment. The McCann case poses issues of real importance which Panorama should have examined. That it is instead running a laboured, pedestrian extended news report is shameful.

But the most important reason for my decision is that because the programme is insufficiently analytical; it verges on the dishonest. Our lengthy investigation revealed that there is no meaningful evidence against the McCanns. Our CBS colleagues concluded that it was 'ludicrous' and 'crazy' to think them involved and that ... 'the child was abducted'.

The real question must be how, without any meaningful evidence, the Portuguese police and the media in Portugal and Britain have been able to convince most people that the couple were involved. Yet while the programme drips innuendos against the McCanns, it does not put a single challenging question to anyone in the Portuguese police or to anyone in the media. This is truly astonishing.

David Mills