One of Suffolk's most unusual incidents took place 40 years ago this month, but what do we actually know about the county's alleged encounter with aliens?

What is alleged to have happened?

Over the course of several evenings beginning on December 26 US airmen based close to Rendlesham are alleged to have spotted strange lights in the sky.

"Guards at the East Gate saw what they thought was a downed aircraft," said retired USAF Colonel Charles Halt, speaking about the case on a visit to Suffolk in 2018.

East Anglian Daily Times: Retired USAF Colonel Charles Halt is considered one of the incident's most credible witnessesRetired USAF Colonel Charles Halt is considered one of the incident's most credible witnesses (Image: Archant)

"It appeared to be metallic from a distance with multiple coloured lights and it was on the ground."

The guards called in their discovery but when calls were made to RAF Wattisham and Heathrow Airport no explanation could be given for what was flying in the area.

Investigators headed out to look for the object.

"Exactly what happened we're not really sure because something dramatic happened to them," said Colonel Halt

Those at the scene reported seeing a triangular shaped craft on legs. The craft was said to be smooth and metallic with hieroglyph style writing on it.

The men returned to base where no one was quite sure what to believe.

The next night another person from the base saw strange lights in the forest.

On the third night Colonel Halt was sent out to sort out what was going on once and for all.

However, when he got into the forest he too had a strange encounter.

"Somebody in the party said look out there and we see this bright orangish-yellow glowing object," said Colonel Halt.

"We watched it for a couple of minutes.

"It comes towards us, through the forest."

Not long after the group spotted further multicoloured lights.

"As soon as the light came on it goes off," said Colonel Halt.

Former USAF colonel talks about UFO sighting at Rendlesham f

In the days following news about the incident spread and began to capture people's imagination.

In the years following those days in December 1980, the Rendlesham Incident would come to be known as Britain' Roswell, the most credible "alien encounter" ever recorded in the UK.

Was it really aliens?

"Even now, 40 years on, I can't tell you what did happen," said Nick Pope, a former MOD investigator who was tasked with looking at the case in the 1990s.

"The mystery remains. The case officially remains unexplained."

East Anglian Daily Times: Nick Pope has written a book on the incident at Rendlesham ForestNick Pope has written a book on the incident at Rendlesham Forest (Image: Chris Loomis Photography)

Despite the lack of an official understanding of the case there are a number of popular theories as to what was seen that night.

One is that the airmen actually saw the lights from the nearby Orfordness Lighthouse some six miles away from where the craft was alleged to have been spotted.

Another suggests that the US Airmen were targeted in a revenge ploy from the SAS who had been captured following a parachuting exercise. The elite British unit is alleged to have got its own back by rigging lights and coloured flares in the forest close to the air base, using black helium balloons and remote controlled kites to carry material through the sky.

Yet another theory often posited is the what the airmen saw were police cars passing through the area.

40 Years On: Britain's Most Famous UFO incident at Rendlesha

What have authorities said about the incident?

While we know there are many theories as to what has happened, improbable as it may seem authorities have taken the possible sighting very seriously over the years.

In January 2018 it was alleged that information regarding the incident might be contained in a dossier held by the US Government's department of defence.

American newspaper the New York Times revealed that over $20 million had been spent on what was known as the Advanced Aerospace Threat Identification Program or AATIP by the Department of Defence between 2007 and 2012.

Another US publication, the Washington Post, stated that a 490 page report from this program contained alleged historical UFO sightings from foreign countries as well as the United States.

This newspaper sent a Freedom of Information Act request to the US Government in 2018 for any information that was held in this dossier regarding the incident.

As of December 2020 the US Government has failed to report back on this request blaming backlog delays.

In the UK the MOD has made clear previously that it does not have any opinion on the existence of aliens and does not investigate UFOs.

Any information it has recorded about the incident has been sent to the National Archives.

What has been the lasting impact of the Rendlesham UFO incident?

Whether you believe in aliens or not the Rendlesham incident has certainly had an impact on popular culture.

Numerous books have been written about encounter with TV shows also exploring the events of that night.

Rendlesham Forest itself has become an attraction for tourists with a special UFO trail created through the forest for visitors to follow.

The impact of those events over 40 years ago continues to be felt, though the truth may never been known.