I saw one of the rarest butterflies in Britain

It is the wood white, and it should appear about now. Not that you will see it fluttering weakly over the fields and farms. It lives deep in the shadiest and oldest forests. It is easily frightened.

Last year I was wandering slowly around a Sussex oak wood, hoping to see one in the first week of June. There were wild roses and bramble in flower in the glade of the dark and gloomy wood.

It was very peaceful there. The oaks were standing like guardians, the birds were silent. Only a few swifts were passing high above and below the clouds. The wood seemed as though expecting the arrival of a special presence, holding its breath. It was warm and humid.

And then it appeared. As if in gauze, this muslin-white sprite tip-toed into the arena and held my attention as if Pavlova had appeared on stage. Just why a delicate and fragile moth-like insect should produce this effect, this midsummer dream, is perhaps not clear to reason. Not everyone would be so affected.

Was it just the rarity of the thing, and nothing more? How can the brain create such a surreality is something we can hardly question. Sometimes it just does. It is a personal thing perhaps. It is magic and that word must do.

For some, the word magic might be used to describe that moment of triumph when a ball enters the goal after a long and hard battle. Or when your favourite equestrian clears the last jump faultlessly.

Maybe it is that moment of a glance from a special person, a child’s message on a scrap of paper, a sound of favourite music whether rock, rap or Rachmaninov. Some brief encounter that stays on for ever.

That is what the wood white did for me as it fluttered on the edge of feeling and knowing. Only the faintest shades of dark adorned its wings, like the first hint of dusk on a summer sky.

Then, true to character, known to science since 1666, it sensed the human watcher and fled the scene, diving deep into the gloomy shadows of the brambles. Still, the sighting was enough to be sure of identification.

Somewhere in Sussex is all I can say, this old woodland with all its secrets. Oh and by the way, the wood white caterpillars feed on birdsfoot trefoil and tufted vetch. They are not the least bit interested in your cabbage plants.