The key question that always crops up when I do media interviews about the MoD files and UFOs in particular is always a variation of: "Do you believe in UFOs?". As I explain in my biography, what they mean of course in not "do you believe that people see objects in the sky they can't identify?" (to which the answer is most certainly 'yes'); what they really mean is: "Do you believe we are being visited by aliens in flying saucers?".
After the yawn I usually refer them to Carl Sagan's response to this very question: "I'm always struck by how the question is phrased, the suggestion that this is a matter of belief and not evidence." So - assuming it matters to anyone - what do I believe?
Personally, I think there's every chance there is life elsewhere in the universe. This is suggested by the recent discoveries of planets circling around distant stars, and the presence of water on Mars. This is a view shared by many astronomers, particularly those identified with the SETI programme (Search for ET Intelligence) - who, as a byproduct of their public statements, have tended to encourage the public to believe in the existence of intelligent aliens.
However, there is a great and significant difference between 'life' and 'intelligent life'. Most scientists agree that the appearance of intelligent life on Earth was the result of chance and an incredible series of circumstances that might be unique to our planet and solar system. What are the chances, then, that intelligent life has evolved elsewhere, and what's more that it has been able to visit us frequently and surreptitiously, for thousands of years, evading detection in the last 50 years by our powerful radars and telescopes?
Therefore, although opinion polls suggest that between one third and one half of the population "believe we have been visited" - the evidence that aliens have come here in UFOs or flying saucers is actually slim or non-existent. And just because lots of people say they believe in something, dosen't make that something objectively real. If it did then we would, for instance, have to accept that the Devil and the Satanic pact with witches was real, simply because thousands of people believed that particular myth during the Middle Ages.
Back to the MoD UFO files. Some commentators are disappointed by the content and are growing tired of seeing tedious bits of paper containing reports of lights in the sky. Where are photographs showing 'structured craft of unknown origin' that would provide clear and unambiguous evidence of the ET presence on Earth? The evidence we've been told the Government has on file, but isn't sharing because we would all panic?
Well, there can only be two answers. Either these photographs aren't in the files because no such evidence exists, or they have been removed by the global conspiracy to hide the truth and salted away somewhere else. This answer is unprovable and takes us nowhere - only into the realms of paranoia.
The answer has to be that no such unambiguous evidence exists. The file contents make it clear MoD's interest in UFOs was purely from a defence point of view. They check to see if sightings reported to them have any "defence significance" (i.e. are they hijacked aircraft, spy planes, enemy missiles?). When those possibilities are ruled out, the reports are simply filed away and forgotten - as anyone can now see from the contents of the released files. Unfortunately, MoD are not funded to scrutinise their UFO reports for their scientific content. They say they remain open-minded about the possibility that ET life might exist, only they have never found any evidence to support the theory.
My opinion is that any genuinely open-minded person who spends a few hours skimming through the contents of these files can only agree with the MoD's conclusions. 90% or more of the reports they received could be explained (if they had bothered to investigate them). The few that remain might be unidentified but unidentified does not necessary mean = alien visitors.
Of course conspiracy mongers will say these papers are a whitewash and the real top secret files are being hidden away somewhere else. But in my experience you cannot have a rational argument with people who have preconceived ideas about cover-ups and conspiracies.