Rosmead is a railway village a few kilometres outside Middelburg in the Karoo, a grid of houses built for the men who worked the junction, with a junior school, a small army camp and a great deal of sky. On a Sunday evening in November 1972 the sky was where everyone was looking.

Around a quarter past eight, four soldiers on duty at the camp reported a set of red lights rotating in the air not far from their duty room. Residents across the village were seeing something too: a bright light, or a cluster of them, that moved in sharp zigzags rather than the smooth arc of an aircraft, and hung about over the town for some time before it went. Nobody heard an engine.

The headmaster of Rosmead Junior School, Harold Truter, went down to his school that evening and saw a light hovering over a ridge beyond it. Closer in, over the school’s tennis court, which had been surfaced with new tar not long before, there was a flickering greenish glow. The court was fenced and locked. He looked through the wire, and as the glow faded he could make out that the tar had been burnt and broken up, and that in the middle of it was a pool of something molten, catching the moonlight. There was a strong smell of burnt oil. He went for the police.

Daylight made it stranger. The court was cracked and scorched across a wide area, and there were holes in the surface, arranged with a symmetry that suggested to the people looking at them that something heavy had rested on legs. Chunks of tar had been thrown clear, some embedded in the bark of the gum trees along the court, some found on a ridge nearly two hundred metres off. A large rock had been shifted a considerable distance. The gum trees nearest the court were burnt on the side that faced it, and within a few weeks they were dead. The police sealed the court and sent samples of the tar to the forensic laboratory in Pretoria.

The answer came back from the top. Colonel Lothar Neethling, the head of police forensics and later a notorious figure for other reasons, announced that the samples showed nothing unusual and that the damage had been done by vandals with pick-axes. Officially, that closed it. Unofficially, according to the local police who had stood on the court, no group of vandals in Rosmead had the strength, the heat or the reason to do that to a tennis court on a Sunday night while the whole village watched lights overhead.

Cynthia Hind, Zimbabwe’s dogged UAP investigator, went to Rosmead years later, interviewed residents and the local historian, and gave the case a chapter in her book UFOs: African Encounters. She found the story had held together. Nobody had come forward with a pick-axe.

That is where it sits. A village of witnesses to lights nobody identified, a physical trace nobody photographed properly, samples that a forensic chief said were ordinary, and a school that had to resurface its tennis court. Rosmead is smaller now, the junction long since quiet, and the court is still there. People still go and look at it. So, for what it is worth, do geocachers, who have hidden a cache nearby with the incident on the label.