As I walked between the huge, crudely shaped standing stones which frame the entrance to this ancient tomb, it was a little disconcerting to see a red light flickering somewhere deep inside the dark passage which lay ahead.
Having had the foresight to bring a torch, it was reasonably easy to make my way down the tunnel, past several openings framed with stone - from one of which another light flickered - to the main chamber at the end.
There, on the dirt floor, was the source of the light, a large red candle, its flame fluttering in the slight breeze from the entrance.
I was in West Kennet Long Barrow, one of the largest and most easily accessible neolithic chambered tombs in Britain, but it had been disused for more than 4000 years, so what was the candle doing there?
For that matter, why was the old oak tree at the start of the path leading up to this hilltop barrow, covered in little pieces of material?
The answer, apparently, is that this particular tomb is a popular place for modern pagans to carry out their bizarre rites.
According to a website on the barrow the candles - there was another one burning in a side chamber - would have been left by modern day pagans conducting a ritual there the night before.
If I had looked more carefully, it seems, I would have found the remains of numerous candles, incense, animal bones and even occult symbols.
And, if I had gone there at midsummer rather than almost midwinter, I might have seen the spectral white shape of a priest walking with his hound who, according to local tradition, haunt the barrow at this time.
Goodness. I think I'm glad I didn't know all this when I strolled up to the barrow on a drizzly afternoon. But somehow I can't help feeling that the people who built the barrow 5500 years before would probably be pleased to know that the memory of the old gods is still being kept alive there ... albeit in strange fashion.
This particular barrow was used for more than a thousand years as a burial place for local chieftains.
The five burial chambers I explored only go a short distance into the mound - about 10m of a structure which is more than 100m long - and are thought to have held about 50 bodies.
About 4500 years ago, the barrow's entrance was sealed with earth, stones and chalk and it lay unused until relatively recent times when the tomb was re-opened, initially looted and later properly excavated.
Now under the jurisdiction of English Heritage and open to the public - including pagans - it is one of an extraordinary collection of prehistoric sites focused on the little Wiltshire village of Avebury.
One of the most remarkable of these sites is Silbury Hill, which I could actually see from the hilltop where the West Kennet Long Barrow sits.
This looks today like a large hill covered with grass, bracken and scrub but, in fact, it is a man-made earth mound, the largest in Europe, about the same size as the Great Pyramid of Cheops and built some 4600 years ago.
The hill is flat-topped, 40m high, covers 2ha at its base and is reckoned to have involved shifting 250,000 cubic metres of earth, a bucketload at a time, yet, remarkably, no one has any idea what its purpose is.
Local legend says that the hill is the last resting place of King Sil sitting on a golden horse, but two tunnels dug from the base and a shaft dropped from the top have failed to find anything beyond dirt, rubble, food scraps and the antler tines probably used as building tools.
Because of erosion problems you aren't allowed to climb the hill but just standing in the viewing area at its base and looking up at its massive bulk serves to emphasise what an incredible undertaking it was and how powerful the motivating forces must have been.
Delightfully, when I brought my eyes back down to earth, I noticed the surrounding area was dotted with freshly dug molehills ... as if even the local moles were trying to imitate this amazing neolithic construction.
Unfortunately, on my visit I didn't have time to see several other ancient sites close by, like Windmill Hill, the remains of three rings of ditches enclosing an area probably used for burial ceremonies, the Sanctuary, a 5000-year-old complex of stone and timber rings which was an important centre for religious rituals, or West Kennet Avenue, a 2.5km long avenue once lined with 100 pairs of standing stones which linked the Sanctuary with the famous Avebury Ring.
Instead, I went straight to Avebury, an extraordinary place, where a delightful stone village, complete with church and manor house, has sprung up in the heart of the largest prehistoric stone ring in the world.
You can still see the enormous outer ring consisting of a huge earth bank nearly 2km in diameter, a great ditch and a ring of 98 great stones.
There are only 27 of the original stones still in place because a few centuries ago many were broken up and used to build the village, but markers indicate where the remainder used to stand, and enough remains to give a taste of what an extraordinary place this must have been.
The largest remaining stone, known as the Swindon Stone, is estimated to weigh 60 tonnes; another, called the Devil's Chair, is said to be able to summon the devil if you run round it 100 times anti-clockwise (I didn't try), and one which was re-erected about 60 years ago is the Barber's Stone, because under it was found the crushed skeleton of a man along with scissors, a lancet and three silver coins.
In the middle of the great ring are the remnants of two smaller circles of stones where religious rites were celebrated.
Strangely, the fact that these ancient structures spring from the grassy fields right alongside houses, a church, a pub and a busy road somehow serves to make them seem all the more remarkable.
Inside one of the old houses is the fascinating Alexander Keiller Museum, run by the National Trust, which commemorates the work of Keiller, a millionaire thanks to the family marmalade business but also a passionate archaeologist.
Keiller devoted much of his life to preserving and restoring the great ring, eventually buying the site, which he later sold to the nation at a bargain price.
The museum includes many of the objects he found during his years of excavating at Avebury, including an amazing array of implements, utensils, domestic animals and, most poignant of all, the skeleton of a young child ... a timely reminder that for all its fascination today this was once a place of ritual and burial, of blood and death.
Every day Emirates has three flights from Auckland and one from Christchurch to Dubai, and flies from Dubai to Britain. Round-trip fares start at $2460 plus taxes but there are specials. See www.emirates.com or call 0508 364 728.
You can find information about all the ancient sites of Avebury at www.english-heritage.org.uk and www.nationaltrust.org.uk
Information about visiting Britain is at www.visitbritain.com.
*Jim Eagles visited Avebury as guest of Visit Britain and Emirates.