Its sensational 'revelations' that scientists were being abducted to work in colonies on the planet Mars in preparation for extinction of human life on earth sent shock waves throughout the world.

%image(14777347, type="article-full", alt="Viewers of the sci-fi spoof were shocked by the film and "inundated" Anglia television with calls. Image: Archant")

But it was little more than an elaborate hoax - and now, 40 years on, the controversial science-fiction drama documentary that terrified viewers and made headlines around the world is to be screened again for its landmark anniversary.

Broadcast as part of Anglia TV's Science Report series, Alternative Three was more fiction than fact, intended for transmission on April Fools Day.

But Anglia TV was unable to obtain network slot that day, meaning it was broadcast on June 20. Just like the 1930s War of the Worlds radio broadcast, calls immediately flooded in from terrified viewers convinced they had seen a genuine documentary, making the hoax national news.

As the 40th anniversary of its only broadcast approaches, the University of East Anglia (UEA) and the East Anglian Film Archive (EAFA) are reviving the cult classic for a free screening at The Forum, Norwich.

%image(14777348, type="article-full", alt="The cast: Greg Monroe, Carol Hazell and Tim Brinton. Photo: ITV Anglia and Christopher Miles.")

Dr Tim Snelson, a UEA media history professor and EAFA director said: 'We would like local people who worked on the programme, which was filmed at the Anglia studios and on location in Norfolk, or local audience members who remember seeing it 40 years ago to come along and discuss their memories with the director.

'Were you taken in by Anglia's elaborate and creative hoax?

'We'll also discuss the film's relevance to contemporary debates about 'post-truth', fake news, trust in experts and climate science, and ask if the hoax reveals a truth about the world culture some 40 years on.

'We are delighted that Chris has agreed to come to Norwich to discuss this fascinating piece of regional television history that shocked the world.'

%image(14777349, type="article-full", alt="Harry (David Baxt) attacks the Anglia crew. Photo: ITV Anglia and Christopher Miles.")

Free tickets are available on a first-come, first-served basis for the event from 7pm to 9pm, on Tuesday, June 20. There will be a question and answer session after the film with director and co-writer Christopher Miles.

'Unlike today, climate change did not dominate the headlines in 1977, but now it seems reality has caught up with us, as often satire can become prescient as the creators had a hunch,' said Mr Miles.