Our screening in Valletta, Malta, and the Q&A afterwards was the closest we’ve come to a riot. I had a fairly good idea of what was ahead when we walked down the aisle in the dark and the back two rows were full of people on their blackberries, not watching the film: the tuna industry.

Malta, of course, is tuna central. Or rather tuna penning central, because the tuna penners use foreign fishermen to catch their fish, to the detriment of Malta’s own traditional fishermen. Malta has also been run by the same political party for over 20 years. And the Government is on the side of the tuna penners. So we weren’t expecting an easy ride.

I had heavyweight support. On the panel beside me were Rashid Sumaila of the University of British Columbia, Craig Dahlgren or the Perry Institute and Caroline Muscat, assistant editor of the Sunday Times of Malta.

The room contained an extraordinary cross-section of Maltese life, including two senior politicians, Paul Borg Olivier, former chairman of Valletta, and general secretary of the Nationalist party, and George Pullicino, Resources Minister a well as senior civil servants.

It also contained Charles Azzopardi, the tuna magnate who owns and operates many of the tuna farms in Malta. You could hardly blame the organizers, GlobalOcean, Nature Trust (Malta) and Friends of the Earth for not doing their job. It was a sell-out.

The questions were nearly all, understandably, about the European Commission’s proposal to place the bluefin on Appendix 1 of the Convention on International Trade in Endangered Species, which could close down the tuna penning industry which brings in around 100 million euros a year or around 1 per cent of the Maltese economy.

These proposals are still opposed by Malta, Spain, Cyprus and Greece. One Prof Carmelo Agius, who works as an advisor to the Federation of Maltese Aquaculture Producers, cast doubt on the famous “escalator moment” in our film when we reveal that on the basis of scientific advice that a sustainable quota was 15,000 tons and the quota set by the Atlantic tuna commission, ICCAT, was 29,500 tons, the actual catch was 61,000 tons.

His query threw me at the time, as no one had raised it even when we showed the film to members of ICCAT’s scientific committee. I asked for the reference which Prof Agius has now provided. And as far as I can see he is wholly wrong. Still says the actual catch in 2007 was 61,000 tons. It revised its estimates in 2008 on the basis of a shorter season.

There was more of the same. One voice from the back asked why we had given time in our film to Roberto Mielgo, a former tuna farmer, who had turned his back on the industry. I said Malta had the greatest respect for a similar figure who had a similar conversion, St Paul. This got the biggest applause of the night.

A senior civil servant said that in his opinion a C.I.T.E.S ban was unenforceable as bluefin could be passed off as one of a number of lookalike species. I pointed out that we had carried off a journalistic first in the film by DNA testing the tuna in Nobu’s London restaurants – all of which turned out to be bluefin from the Mediterranean. There are companies who offer the same traceability tests to Brussels inspectors.

Rashid Sumaila pointed out that over-fishing in Africa was one of the reasons why Malta is plagued by illegal migration. Caroline Muscat pointed out that a ban on international trade would not stop local fishermen plying their trade but would stop the industrial methods the tuna pens depended on which were wiping out the tuna.

Then the rotund figure of George Pullicino got to its feet. Mr Pullicino argued that international trade in the tunas should not be banned but regulated by ICCAT. I said that this organization had failed to do that over the past 40 years.

Then he asked whether the British, portrayed in our film by Ben Bradshaw, the then fisheries minister, would have been happy for the cod to be listed under C.I.T.E.S. Appendix 1. I began an answer, in which perhaps foolishly I said that the circumstances were not identical, only for the room to erupt into shouting. A fisherman in front of the minister shouted out his question and the hecklers at the back joined in.

The panel discussion was brought to an end and Fat George was able to slip away without answering a number of questions which seem pertinent. Why does he support the most lucrative part of the tuna industry which is most likely to cause its collapse, rather than the most sustainable, traditional part? When does he think the tuna population will collapse below the point of no return, because at the present rate of exploitation that is inevitable? And most pertinently of all, why is he continuing to assert Malta’s outright opposition to an international tuna trade ban instead of negotiating the best compensation package for the largest number of Malta’s fishermen, because the largest tuna penners are already diversifying into other businesses?

To my surprise as we all trooped next door for a drink and a canapé, I found myself shaking hands and sharing a drink with some of those who had been shouting, particularly the fishermen. The heat of the moment had passed and they were being hospitable. I was discovering one of the most charming things about Malta.