Taylor was checking the progress of new saplings when he saw what he described as a large, circular sphere approximately seven yards (6.4 metres) in diameter, hovering above the forest floor.

He said the object was "a dark metallic material with a rough texture like sandpaper". The outer rim was "set with small propellers".

As he approached, two smaller spheres, each about three feet wide with protruding metal spikes "similar to sea mines", dropped down from the mother craft and rolled towards him. Taylor claimed to have experienced an acrid smell "like burning brakes" and the sensation of being dragged.

Taylor said he then lost consciousness and awoke to find the objects were gone. Head pounding and with a bitter taste in his mouth, Taylor was unable to walk or talk.

Eventually he managed to crawl to his van parked nearby but couldn't start it and had to walk the mile to his Livingston home.

Taylor's wife, shocked by his disorientated and dishevelled appearance, called the police and a doctor. There were grazes on Taylor's legs and chin, but no other signs of injury; although the heavy work trousers he had been wearing were ripped.

The police returned to the site with Taylor where they found "ladder-shaped marks" in the soil where the craft was said to have hovered, and further marks following the path of the mine-like objects.

The case remains unique in British history as the only example of a UFO sighting becoming the subject of a criminal investigation. Taylor, who died in 2007, never sought publicity or financial gain – and always stood by every word of his account.

There would later be suggestions that he had suffered an epileptic seizure, mini-stroke or hallucinated after ingesting deadly nightshade berries. Yet, Ron Halliday, co-organiser of the Scottish UFO and Paranormal Conference 2018, gives short shrift to such theories.

"There was no evidence that Bob had any illness before he had this encounter," says Halliday. "He was always personally convinced that he had seen something 'out of this world'. Everyone agreed that Bob was a sincere person. He hadn't made anything up. Something had happened to him.

"He definitely did see something 'out of this world' because I don't know what else can explain what he saw. There was physical evidence that something had been there and clearly something had happened to him.

"I would say that of all the Scottish cases it is the one that seems to me that gives the most direct evidence of contact from another world."

UFO capital: Bonnybridge and the 'Falkirk Triangle'

The phenomenon of the "Falkirk Triangle" – which includes Bonnybridge and Camelon – was first reported in 1992 and the area continues to register more UFO sightings, around 300 a year, than any other place on Earth.

Objects spotted range from "big, black and cigar-shaped" to "a bright light criss-crossed by stripes of different colours".

In October 1996, local man Barry MacDonald captured a video of an orange oval light in the skies above Falkirk which changed shape as he watched, becoming a white disc – the classic "flying saucer" shape. The clip went viral worldwide.

According to Halliday, the "Falkirk Triangle" continues to be a UFO hot spot. "What is interesting about this area is that there has been an accumulation of incidents stretching from the early 1990s right up until last year," he says.

"One theory is that there could be a window into another dimension, other worlds, the past or the future. These views are controversial – I understand that. There have been so many incidents reported that it's clear something strange has gone on in that area."

Blairgowrie: Crop circles and balls of light

Crop Circles - Balls of Light

Sid and Gwen Freeman from Blairgowrie, Perthshire, experienced a series of odd incidents during April 1984 that included a UFO hovering over their garden and a visit from 12 men dressed in black.

Halliday believes the area surrounding the town is another hotbed of UFO activity, with reports of strange balls of light in the sky and the location of Scotland's first ever crop circle in 1990.

The most bizarre incident is what could be a UFO crash reported in the Annual Register of 1767. It described a pyramid-shaped object over the River Ericht that moved "with great speed and disappeared a little above Blairgowrie" leaving a trail of destruction in its wake including a partly destroyed house and bridge.

"You do find some areas seem to attract certain events and it is hard to explain precisely why," says Halliday. "But they do seem to be connected in some strange way."

West Lothian: The A70 Abduction

There have been many reports of glimmering discs, strange lights and bouncing balls of fire in West Lothian skies since Robert Taylor's 1979 encounter.

Garry Wood and Colin Wright had an unnerving experience on August 17, 1992, while travelling on the A70 near Harperrig Reservoir where they saw a two-tiered, disc-shaped object above the road.

Wood put his foot down on the accelerator to speed away, but as they passed beneath the UFO, it appeared to emit a "curtain of white light" and the pair reported being temporarily enveloped in a black void for what felt like 10-15 seconds.

The car began shuddering and they emerged to find themselves driving on the wrong side of the road. When Wood and Wright arrived in the South Lanarkshire village of Tarbrax, where they were due to drop off a satellite TV system, they discovered that several hours were unaccounted for.

Afterwards they underwent hypnosis sessions, with both men recalling an alien abduction scenario and being subjected to a medical-type examination.

"I have spoken to both Garry and Colin – in fact, I have spoken to Garry several times – and there is no doubt in my mind they're convinced that they had this strange encounter," says Halliday.

"The criticism in that case was that the story of the actual details of the encounter – the abduction – had only come out when they went under hypnosis. Hypnosis is quite controversial because of false memory syndrome.

"Interestingly, just a couple of years ago I was speaking to a chap who had no interest in UFOs, but he said to me quite spontaneously that he had been driving along the A70 and had come to this stretch of road and there was this huge bright light overhead which enveloped the car.

"That was very similar to what happened to Garry and Colin, but he didn't experience an abduction."

Forth Rail Bridge: A surprise centenary visitor

The centenary of the Forth Rail Bridge was celebrated on October 7, 1990, with a fireworks display. Watching the festivities was Lyn Livingston who caught sight of a circular object with a base made up of intermittent red, white and blue lights in the sky.

The UFO is said to have rotated and appeared to change shape, forming a projecting cone of white-coloured lights. It stayed in position for 15 minutes before drifting off towards the Fife coast.

"There was a number of witnesses to that," says Halliday. "The location is part of this triangle of incidents and activity, stretching over from West Lothian into Fife. It got a lot of publicity at the time because a few people claimed to have seen it."

Glasgow: The flying railway carriage

Tom Coventry* was waiting at a bus stop on Menock Road near King's Park, Glasgow, when he claims what looked like a railway carriage-shaped object passed 20ft above his head.

The incident took place in December 1983, with Coventry reporting being able to see three windows at the front and a glimpse of swirling yellow smoke inside.

"He had this experience, which has been reported in other UFO sightings, where he had a sense that everything had stood still," says Halliday.

"It was almost like he was in another world for a moment as he watched this object passing over. I spoke to him several times and queried it, but he remained convinced that he saw this object."

In the west end of Glasgow two UFO incidents – 21 years apart – were reported within the same, small geographic area. The first, in 1955, was at Belhaven Terrace where children playing outside were terrified by several entities floating above the ground dressed in long white clothes.

Another incident is reported to have happened in nearby Westbourne Gardens in 1976. "A chap saw this silver disc-shaped object coming towards his flat window," says Halliday.

"He was dumbstruck by it. He described it as hovering about 100ft above an open space opposite where he was standing. There were other witnesses in two nearby flats who also saw it."

Dunblane: UFOs in the hills

David Evans* claimed that UFOs regularly flew over his home and that they had a base inside hills near Dunblane. His experiences began in 1992.

"I visited his house at Kinbuck near Dunblane and there was a little hillock in his garden," says Halliday. "He had been standing there when he saw this UFO fly over the top of him.

"He also believed that he'd had some UFO interference in his house where something – he wasn't sure what – had come in and disturbed various things.

"The most curious part is that he said he saw these UFOs disappear into a hill. He pointed out these white things to me. It was quite a distance away, but I did see round, white objects on the hill. They were so far away, however, that exactly what they were I don't know."

*Some names have been changed

Inside track: Scotland's X-Files Investigator

RON Halliday has been fascinated by unexplained phenomena since he was a child. The retired assistant registrar from Bridge of Allan has written nine books covering subject matter from UFOs and ghosts to vampires, witches and other supernatural experiences.

Alongside fellow investigator and author Alyson Dunlop, Halliday is co-organiser of the Scottish UFO and Paranormal Conference 2018 which takes place in Glasgow on Saturday.

He will be giving a talk, Mysteries of the Scottish Landscape, unravelling secrets behind standing stones, crop circles and ley lines among others.

How did you first become drawn to this field?

My granny was a psychic and forever seeing spirits of the dead. I was a bit scared initially when she would talk about ghosts, but I got used to it and began to get interested. My dad was a scientist, so I come at it from that side too.

Later I became interested in UFOs and that expanded into what I would call "mysteries of the landscape" such as ley lines, crop circles, mystic sites and so on. I think it all could be connected in various ways that may not seem obvious at first.

Sometimes UFOs are described as having a ghostly appearance; they come and go. It is the same when people see ghosts that appear solid and then seem to vanish instantly.

One theory is that witnesses to these incidents could be seeing into another dimension, other worlds, the past or the future – almost like looking through a window.

Many people associate UFOs with little green men in flying saucers. What are your thoughts?

One of the puzzles of the whole UFO phenomenon is that people do report different shaped objects and types of aliens.

An interesting case involved a 10-year-old girl who went out into the woods in Meigle, Perthshire, and came across a group of small, blue beings. She was beamed up into what she presumed was a spacecraft and these aliens looked at her. Afterwards they beamed her back down.

She arrived home to discover she had been gone for hours and her parents were about to call the police. In Scotland, blue traditionally was the colour associated with the supernatural such as Blue Men of the Minch and the Blue Stane in St Andrews.

Why does Scotland have such a rich history in supernatural tales and paranormal experiences?

I wish I had an answer to that. People talk about Bonnybridge being the UFO capital of the world. We have some of the most famous monsters in the world at Loch Ness and Loch Morar. It is hard to explain precisely why this happens.

If I come back to this idea of opening up a window into different dimensions, then perhaps for some reason Scotland has a particular interaction and connection with other worlds.

The Scottish UFO and Paranormal Conference 2018 takes place at Queen Margaret Union, University of Glasgow, from 10am to 6pm, on July 28. Tickets cost £10. Visit scottishufoandparanormalconference.wordpress.com

UFO Scotland by Ron Halliday is published by Black & White and available on e-book.