Britain’s Air Secretariat 2A1 has closed for business – which means the Ministry of Defence (MoD) won't be investigating any more UFO sightings. But they've left their records behind: 11,000 of them, representing 50 years of UFO reports. Last Thursday, the British National Archives released thousands of them.

Nobody can accuse the Brits of not taking the threat of aliens seriously. A scroll through the archive reveals page after page of handwritten forms, filled in by officials who meticulously noted the most mundane aspects of each case: “He went and got wife out of bed to see ‘it’ (the UFO)”, says one.

There are more exciting reports in amongst them, like the one about the triangular UFO that hovered over the backyard of a Birmingham man in 1997. It then dropped a ‘milky white substance’ on his trees before flying off, which the man collected – unfortunately, the jar’s been lost to posterity.

Or there was the UFO that apparently hovered above the house of Michael Howard, the then Home Secretary (the minister for national security). In March 2007, six members of the public, including two firefighters, alerted the Royal Air Force to a triangular, “humming” craft above his home.

The official notes of the incident state the “MoD air defence staff have confirmed there is no evidence to suggest any unauthorized incursion of the UK air defence region on that date”.

Then again, maybe they didn’t look very hard, because the MoD was getting sick of UFOs  – and the people who reported them. According to The Guardian, the MoD had to blank out “uncomplimentary comments” about the public before releasing the files.

Their exasperation occasionally shines through: “Abduction is a criminal offence and as such is a matter for the police to handle,” as one enquirer who reported an alien abduction was told. “The police can only investigate allegations of abduction if there is evidence to suggest that such a crime has taken place. “

Unfortunately, even as the MoD was giving up on UFOs, the public appetite for them was growing, fuelled by programmes like The X Files. According to Nick Pope, who used to run the British Government’s UFO Project, “at one time, MoD was receiving more FOI (Freedom of Information) requests on UFOs than on any other subject”.

So in 2007, a decision was taken to release the UFO files to the public, over three years. Sitting alongside the documents is chapter two of The UFO Files, a guide to the files written by UFO expert Dr David Clarke. His book details how the MoD came to be interested in UFOs in the first place – they were alarmed by apparent alien activity at Andrews Air Force Base in the US in 1952. Winston Churchill wrote a note about it, which is in the archives: “What does all this stuff about flying saucers amount to?... Let’s have a report at your earliest convenience.”

As it turned out, many UFO ‘sightings’ were just blips on the radar. Until the 1950s, the path of migrating birds had never been tracked; the ‘angels’ appearing on radar turned out to be birds. To prove it, Clarke says, the RAF got hold of some dead birds, wrapped them in cellophane and whirled them around on sticks, to measure their ‘echoing’ area.

The UFO files will be available to download for another three weeks. Sadly, they’ve come too late for Gary McKinnon, a UK citizen facing extradition to the US for hacking. McKinnon hacked into 97 US military and NASA computers, seeking evidence of a UFO cover up. Unfortunately, his efforts not only shut down the US Army’s Military District of Washington computer network for 24 hours, but also deleted US Navy Weapons logs – in 2001 and 2002.

McKinnon has become a cause célèbre in Britain, with high profile figures fighting his extradition.

But the real question, of course, is did he find anything while hacking?

He certainly did. McKinnon, who has Asperger’s Syndrome, claims that not only did he find pictures of alien aircraft, but also an Excel spreadsheet headed ‘Non-Terrestrial Officers’.

Maybe somebody should tell Britain’s Ministry of Defence that it’s too early to shut Air Secretariat 2A1 just yet.