UP AHEAD, the sleek outline of the big cat is unmistakable. The black muzzle thrusts forward in search of its prey. The ears are cocked, straining for every sound. Every taut muscle suggests a stealthy strength, economy of movement and lightning speed.
Little wonder, then, that the Lynx courier service van - with its trademark black cat painted on the rear of the vehicle - starts pulling away from me with ease as I journey north up the M90 towards the rich farmlands of north-east Scotland. My job is to track down the mysterious and elusive Beast of Buchan, a giant cat that has been emerging from its hiding place over the years to take the odd sheep, strip its carcass clean and strike fear of the unknown into humans.
There has been a steady stream of sightings this year, but nothing in the way of real evidence that the Beast actually exists. I'm hoping - no, praying - that my motorway encounter with an artistic representation is not the closest I am going to get.
Big-cat sightings are now, like Nessie, almost part of Scottish folklore, stretching back to the 1930s. Although the Beast of Buchan is perhaps the best known - like the Beast of Bodmin Moor, it has a lovely alliteration that only serves to propagate the myth - sightings are regularly reported across the country, from the southernmost reaches of the Borders to the north of the Highlands.
Of one thing all who see it - or them - are certain. The Beast is not a native Scottish wildcat or a strange, overgrown hybrid mutant of the domestic moggy. Some swear it is a lynx, others a puma, many a black panther. It's the size of a labrador, alsatian, greyhound, take your pick, but it's not a dog or even a fox. So prolific have sightings become that the Beast now has its own set of stalkers, the Scottish Big Cat Trust. This dedicated, if loosely connected, band of followers, will investigate sightings wherever they occur.
Among this intrepid band is George Redpath, a true believer who took a job as a police wildlife liaison officer in Fife partly to give him the opportunity to track down big cats. Now retired from the force, he admits to being obsessive about his hobby, meticulously logging sightings phoned in to him from all parts of the country. His study is lined with books on the phenomenon and stacked with numerous bulging files of notes.
So how many big cats are out there? Redpath doesn't like being pinned down on numbers, but he eventually hazards a guess at around five in Fife alone and 50 across Scotland. How did they get there? "No one really knows," he shrugs. "But I do know that they are there, because I have seen them myself."
One theory that he and other enthusiasts subscribe to is that pumas, jaguars and panthers were released into the wild in the mid-1970s. Until the passage of the Dangerous Wild Animals Act, in 1976, owners could keep big cats as pets, whether in their homes or in private menageries. Faced with the expense of building cages and a tortuous licensing scheme, some chose to set their animals free rather than have them put down. Those at large today could be the offspring.
"Pumas can survive in this environment," Redpath insists. "There are lot of rabbits and small deer to eat. Both the puma and the black leopard [panther] are secretive, solitary animals, so it is no surprise to me that they can successfully hide."
Redpath first became interested in big cats while serving in the armed forces in the jungles of Malaya during the 1950s. After joining the police force, it was a fellow officers' disbelief when a sighting was reported that spurred him on to take the wildlife liaison job. Even then, it took ten years before he had his first close encounter, in 1998, near his home in the village of Balmullo, just south of the Tay bridge.
"Farmers had been reporting dead sheep and I got a call of a sighting just after I had finished work at 3pm," he says. "It was on the hill above the house, so I grabbed my camera and raced up there in the car. One of the local farmers was out searching for it with a gun. I couldn't see anything, and I was just about to turn around and go back down the hill when I saw it. It was a big, jet-black cat, sitting on its haunches. But as I tried to get closer it turned around and disappeared into some nearby bushes.
"Since then I have seen one closer than that. It was quite dark, but I saw it walking down a dyke and then disappear into the woods. These are not native cats. Scottish wildcats do exist, but the animals I am talking about are much bigger than that.
"Of course, there is scepticism about whether they exist at all, but that's only because these animals are not supposed to be here. Not all the sightings I get told about are going to be big cats; when it's dark people make mistakes and think they see all sorts of things. But there have been too many to dismiss them all."
Around 35 sightings have been logged in Fife alone this year, the latest only last month, near Cupar. George Brown, a 42-year-old telephone engineer, his partner and three-year-old son say they watched a "puma-like" animal with a long, black furry tail for around 15 minutes. When I say goodbye to Redpath and drive north through the darkening Fife countryside, I make sure that the car doors are locked.
Sightings there are aplenty - 50 of the Beast of Buchan in the last six years alone - but given the supposedly ferocious nature of the big cats in question, it seems remarkable that there have not been more attacks on humans. The only 'victim' whose story has emerged so far is Doris Moore, who says she was attacked by a mystery animal close to her home, near the Aberdeenshire village of Insch, in January 2002. She says the animal struck as she was leaving a steading where her horse was stabled. It clawed at her leg and she reacted by striking it with a bunch of heavy keys. It retaliated by sinking its teeth into her leg before fleeing. A friend who rushed to her aid said it was a "sleek black beastie", about the size of a labrador but with a feline appearance.
More details are hard to come by, as Moore now refuses to be interviewed about the experience, saying she has been ridiculed ever since. But regardless of what attacked her, Insch appears to be within the Beast of Buchan's ever-expanding range. There have been more recent sightings in Bridge of Don, Braemar and Belhelvie, confirming the theory that the Beast likes nothing more than a place name beginning with B. Other sightings, in Inverurie, Ardersier and Fraserburgh, only serve to confuse the picture.
I seek clarification in the Cock and Bull, a hostelry on the A90 road from Aberdeen to Peterhead, where a notice above the door declares "Stories are told here". This looks promising.
The no-nonsense manager simply looks bemused when I invoke the Beast's name, but she beckons a younger barman over. "Oh, yes," he says, "people say they have seen big blacks cats on the old railway line. That's probably the best place to look." Encouraged, I down my coffee, thinking I can do better than that. Next stop is Cruden Bay, the scene of the Beast's latest crime.
The pictures tell the story. A tangle of wool lies on the ground, the almost unrecognisable remains of a six-month-old black sheep that had been doing nothing but quietly grazing on the cliffs above the picturesque Buchan village. A ribcage and backbone ripped out of its body and cleaned of flesh bear witness to the violence of its death.
Jim Cantlay is the sort of practical Buchan farmer who would once have laughed dismissively if you had told him that a big black cat was roaming the fields. Since 2pm on October 16 this year, though, he is not so sure. Now retired, he was up on his old stamping ground checking hay bales when he noticed the wool tangle in the middle of a nearby field. "I went over to see what it was. There wasn't much left of it," he says. "There was the head and the legs and the backbone, and that was it. The carcass had been dragged about 20 feet, and you could see the trail of tufts of black wool."
He now insists that only a big cat could have inflicted such injuries. "I have raised sheep all my life and I have never seen anything like it," he said. "I have seen dogs kill sheep, but they will just tear a few lumps out. Same with foxes. That's why I think it must have been something else. The rest of the sheep were all huddled in the far corner of the field, as if something had frightened them. That is not normal behaviour unless they are really scared."
Despite all his years on the cliffs, Cantlay has never seen a big cat in the area, and neither have his family. However, Albert and Sheila Jackson, on the neighbouring farm, have. "No, we hadn't been drinking," laughs Sheila, who took over the farm from her family six years ago. "It was just before lunch. I have never seen anything like it before, or since: a big, jet-black cat, much bigger than a wildcat, about three feet long with a long tail. We watched it by the fence and then it came up towards the house, walked along the field and then came back again. It just slunk along and kept looking at us. It was in view for about 20 minutes."
The couple now have a camera at the ready should the creature return. "I'm not worried," says Albert. "I would love to see it again."
He should take walks with Terry Wright, who lives five miles up the road, at Boddam, a village just to the south of the fishing port of Peterhead. Wright, an affable retired engineer, says he has seen the Beast many times while out walking his dog. Huddled in his home overlooking the lighthouse built by Robert Louis Stevenson's grandfather, Wright says he has encountered the Beast - or Beasts - "countless times" as they wander the rough coastline between Cruden Bay and Boddam. "There's two of them up there," he discloses nonchalantly. "One's a small puma and the other is a black panther. It is a beautiful, full-grown animal, about six feet long and in fantastic condition - you should see it when the sun shines on its fur."
Local farmers have complained about mysterious sheep-kills, he says, and he once watched from a hiding place as the panther dismembered a deer. "But I'm not going to tell you exactly where, because I'm afraid someone will go out and shoot it as a trophy. But would you like to see what I call the 'butcher's table'? It's where it sometimes takes its kills." Now we are getting close.
The butcher's table is a small area of flat, muddy ground surrounded by the red granite outcrops that give the cliffs above Boddam their hard edge. Just a stone's throw away, a flock of sheep munch unconcernedly in a rough field behind a flimsy fence. No panic there. To the left, steep cliffs tumble down to the great expanse of the North Sea. To the right, across a railway cutting and up a steep rise, motorists plough past on their way to Aberdeen. If it's solitude the Beast craves to devour its prey, this seems an unlikely spot.
But Wright bends down to point out what he claims are panther claw marks in the ground. In his favour, there is a set of uniform scratches that could be interpreted, in a certain light, as having being made by a large animal. "This is where it brings its prey," he says. "I've seen it drag something on to the old railway, and when I looked over at it, it just looked back at me and kept on eating. It doesn't seem to see me or the dog as any sort of threat."
So, after 24 hours of intensive hunting, I've met six people who would swear that the Beast exists. At least four of them have seen it and none of them seems (too) crazy. Time to call in the experts.
Darren McGarry is the animal-collections manager at Edinburgh Zoo, which has strictly enclosed black jaguars. Do big cats exist out in the wild? "No," says McGarry emphatically. "I don't think there is a jaguar or a leopard or a panther living out there. If there is anything, it is some sort of hybrid of the Scottish wildcat or a hybrid of domestic cats. The people who say they have seen things have seen something, but it is not a big cat. They may have seen something black, but that is most likely a result of the lighting conditions. If it was a big black cat there would be more sightings, and there would have been more attacks on humans. There are no big cats out there."
Try telling that to Karen Holmes, who was out walking in the early evening near her home in the Borders village of Townyetholm, near Kelso, earlier this month. After seeing lights, she crossed a field to confront some youths she thought were hunting foxes. "Then suddenly I saw a big cat about 50 yards away," she says. "It was a black panther, crouching and obviously stalking a rabbit. I just started backing off very slowly, because if I ran it might have gone for me. I watched if for about ten minutes."
She says she recognised the animal as a big cat because she had seen it twice before, in daylight. "It has the ears and muzzle of a big cat," she says determinedly. "I know what I saw."
The truth may be out there, somewhere. Unfortunately, I - like many others before me - have yet to find it.