It’s not even closing time at the Red Lion in Avebury and there is already witchcraft afoot in the field next door. Nobody is in the least bit surprised and this alone speaks volumes about the interesting mix of characters you find in an average English village, except that Avebury is anything but an average village.

It stands in the centre of an enormous stone circle – fourteen times the size of Stonehenge – and arranged around the inner perimeter of a precipitous 4500 year-old ditch and bank. The great 17th century antiquary, John Aubrey put it best when he noted it ‘doth as much exceed in greatness the so renowned Stonehenge, as a cathedral doth a parish church’.

Leaving the pub, I venture out into this cathedral and notice the bob and swing of hand-held lanterns on the far side of a dark field punctuated with sarsen monoliths. Despite tonight’s full moon, slowly rising over the clutch of thatched cottages at Avebury’s centre, there seems precious little light about and I stumble over a short wall, up and down kerbs, over a stile and across rough ground, cursing the darkness with every step.

I have come to catch the Ogam Observance of the Full Moon – a druidic ceremony that marks the exact moment of the moon’s zenith. Tonight, the exact moment turns out to be just after three in the morning and though I am willing, my B&B is a mile up a road on which motorists observe only the reckless pursuit of Swindon, tending to drive in a manner that makes matters tricky for the hapless moonlit pedestrian.

Fortunately, I have met Gordon Rimes, a 61-year old Wiccan priest with a kindly avuncular manner and – as it turned out – a day job as a balloon artist of some standing. Gordon told me he’d be ‘doing something’ tonight – a pagan ritual known as an ‘Energy Raising Circle’ – and invited me to come along.

I stumble across the field and find Gordon resplendent in a long green robe and a fake fur jerkin laying out lanterns at the cardinal points of a small imaginary circle. A larger, wilder flame flickers in the centre and on the eastern side, two lanterns form a metaphorical doorway through which all exit and enter.

I say ‘all’, but there’s only two of them there – Gordon and a woman I didn’t quite catch the name of. I am invited to either remain on the periphery and watch, or join the circle and participate. I decide to join in.

Drawing an imaginary gateway on the side of the circle, Gordon invites me in. Immediately, the four elements are beckoned – by bellowing ritual jargon at them – to come and join us in the moonlight. We all join hands in the circle. Being British, I find that the novelty of holding hands with strangers is almost a religious experience in its own right and I begin to tingle for cultural reasons. We walk, gather pace, then run clockwise around the circle. The others begin to sing but I don’t know any of the words and have lost the tingle by the time we come to a halt.

After a moment of reflection, off we go again, wheeling around hand in hand, singing, invocations flung out into the night like bats lobbed from a fast car on a roundabout. In this flurry, Gordon mentions a horned god of some kind, but the moment to check we aren’t alluding to Satan is whipped away in frantic dance. The vortex grows wilder still, hands are released and we fizz around like unstable electrons. The circle is briefly chaotic and Gordon acquires a puckish effervescence in his eyes.

I’m not really given to singing and dancing in public – not even in a dark field with a limited audience, so I’m grateful as things settle down a bit and offerings are made, but even here there are surprises. When we met earlier, Gordon confessed that he doesn’t always play it by the book and some Wiccans probably take issue with his interpretations of pagan rituals.

His choice of offerings – traditionally cake and ale – could raise a pagan eyebrow or two. On the one hand, we drink mead from a chalice – which seems old-school-spiritual enough, even though Gordon boasts that he bought it in Morrisons for £3.74, but for ‘cake’, we pass around a bowl of ready salted crisps.

At almost midnight our hosts wind things up by scattering the remnants of crisps to the four elements and thanking them in turn – air, fire, earth and water – each to a chorus of ‘hail and farewell’. Final words are spoken – ‘merry meet and merry part and merry meet again’ – and we go our separate ways, a little lighter, under the watchful gaze of the still waxing moon.