A list of attendees at a climate-change seminar the BBC has spent tens of thousands of pounds trying to keep secret has been unearthed on an internet archive. The listed names emerged after the publicly-funded broadcaster fought off requests for the list under freedom of information (FOI) laws.

This surreal story is only tangentially about climate change: the disclosure raises questions about the evidence submitted to the information tribunal by the BBC and Helen Boaden - its director of news who "stepped aside" this week.

The case also highlights once again the BBC's corporate strategy of using an FOI derogation, or legal "opt-out" clause, to withhold a wide range of material from citizens who wish to know whether the BBC is fulfilling its statutory obligations under its royal charter.

And it raises further questions about the effectiveness of the BBC Trust. The trust, which replaced the Board of Governors, was created with a mission: an "unprecedented obligation to openness and transparency". It has yet to enquire into the corporation's use of FOI derogation to withhold data such as the BBC's US tax contributions, website statistics, and strategic policy-making decisions.

A 'brainstorm' that became historic

The seminar whose attendees the Beeb sought to keep secret was birthed by three organisation. In 2004, the International Broadcasting Trust - a lobby group funded by a number of charities, including many involved in campaigning on climate change - devised the first in a series of seminars on development issues, where the lobbyists could address broadcasters.

One event on 26 January 2006 was a "brainstorm", in the IBT's own words, "focusing on climate change and its impact on development". The BBC sent 28 senior staff, and 28 outsiders were invited. The event was also organised by CMEP, its second parent - a now dormant or defunct outfit operated by BBC reporter Roger Harrabin and climate activist Dr Joe Smith, and once funded by the Tyndall Centre at the University of East Anglia (UEA) and pressure groups.

Harrabin later explained that the BBC's head of news in the 1990s, Tony Hall, had invited him "to devise meetings with politicians, business people, think tanks, academics from many universities and specialisms (science, technology, economic and social sciences, and history), and policy experts and field workers from NGOs – particularly from the developing world".

The third parent of the seminar was the BBC.

Normally such a talking-shop would have no great significance. The 2006 seminar, however, subsequently became very important indeed. The following year a thoughtful BBC Trust report on impartiality cited the discussion there and said it had settled the argument - as far as the BBC was concerned - on climate change.

Filmmaker John Bridcut wrote:

The BBC has held a high-level seminar with some of the best scientific experts [our emphasis] and has come to the view that the weight of evidence no longer justifies equal space being given to the opponents of the consensus [on anthropogenic climate change].

The BBC is under a statutory obligation to remain impartial, so this gave the "brainstorm" a historic significance: the BBC has not previously abandoned impartiality in peacetime.

A blogger, Tony Newbery, was struck by the difference between contemporary evidence that the seminar was educational and composed largely of activists - as confirmed by Harrabin - and the trust's insistence that it was a sober scientific presentation that could justify a historic policy change. (The BBC Trust has done nothing to disown or qualify Bridcut's description of the event.)

Fresh light was shed on Harrabin's CMEP in 2010, in the second batch of Climategate emails. An email from Mike Hulme, the director of the Tyndall Centre for Climatic Change Research at UEA, complained about a BBC Radio 4 item broadcast in February 2002. The piece featured global-warming sceptic Professor Philip Stott and Sir John Houghton, who was a Met Office chief and the editor of the first three IPCC reports on climate change. Houghton came off worst, and an infuriated Hulme wrote:

Did anyone hear Stott vs Houghton on Today, Radio 4 this morning? Woeful stuff really. This is one reason why Tyndall is sponsoring the Cambridge Media/Environment Programme to starve this type of reporting at source.

Newbery filed his FOI request for the seminar's attendees to the BBC in 2007 and was rebuffed, setting him on a long path that culminated in a second round of information tribunal hearings a fortnight ago. The cross-examination of the BBC's Helen Boaden in a court room was reported here.

The BBC is regarded as a public authority by the Freedom of Information Act 2000, but it can withhold information held "for the purposes of journalism". But how wide should this derogation be?

In an earlier and separate FOI case against the BBC, Supreme Court Judge Neuberger argued the opt-out should be interpreted narrowly - otherwise the BBC could withhold information about "cleaning the board room floor" using the journalism get-out clause - an absurdity.

In the Newbery case, the BBC maintained that archival material on the seminar could not be found, but also it should not be found: as a back-up argument it argued that the seminar was held under the Chatham House Rule - an agreement of etiquette, rather than a law, to prevent quotes being attributed to particular speakers at a meeting - information that Newbery did not seek.

On Friday the tribunal ruled decisively against Newbery, and for the the BBC.

Case closed? Think again

However science writer Maurizio Morabito has unearthed a list - once hosted on the IBT's website and now stored in the Wayback Machine's cache of the internet.

It confirms the accuracy of Harrabin's description of the composition of the invitees, with most coming from industry, think tanks and NGOs. And as suspected, climate campaigners Greenpeace are present, while actual scientific experts are thin on the ground: not one attendee deals with attribution science, the physics of global warming. These are scarcely "some of the best scientific experts", whose input could justify a historic abandonment of the BBC's famous impartiality.

Intriguingly, Tony Newbery had been supplied with a later version of this document, he tells us - but with the attendee list stripped out.

Newbery says he has written to the BBC's solicitor to confirm whether the Wayback Machine IBT list is accurate.

The dramatic appearance of the list raises many questions. Did the BBC know the information was publicly available? If so, why were corporation lawyers spending thousands of pounds to keep a public document "secret"? (FOI requests for public information typically state, quite simply, "this information is public".) How much is this legal strategy costing TV licence-fee payers? (An FOI attempt to obtain legal costs in the similar case Sugar vs BBC was rejected by the BBC.)

Questions abound this morning on Twitter about the ability of the BBC Trust to maintain its duty to transparency. The BBC's legal strategy entails the indiscriminate application of its FOI derogation "for the purposes of journalism" - this effectively rewrites the 2000 Act, and redefines the BBC as a private body. The trust is surely aware of this; it has a small mountain of correspondence on the subject. But it has yet to enquire, let alone pronounce on whether this is healthy - or legal.

The trust could do worse than start here - where the BBC refused to disclose how much US tax it paid, because - you've guessed it - the information is required "for the purposes of journalism".

Click to the next page for the list of attendees, according to the discovered IBT document. ®