In December 1968 Lourenço Marques was still a Portuguese city, and the South African consul-general in it had a boat to finish. He had imported two fibreglass hulls and a set of plans for a catamaran from England, and a master woodworker from Pretoria, a friend who had once done work on his house, had railed the half-built yacht down and come to stay over the builders’ holidays to rig the mast. The boat was kept at the Clube Naval, on the sea front south of Polana beach. That is the level of detail the consul-general gave, twenty years later, when he sat down to write out for Cynthia Hind’s new magazine the one thing that had happened to him in seven years in Mozambique that he could not explain.

On Friday 13 December, at about three in the afternoon, the two men were in the back of the consular car, the chauffeur driving, going east down the Avenida da República past the showgrounds and the fishing club. The road rounds Ponta Vermelha, the red point, and turns north along the sea with the cliff on the left and the whole of the bay open to the east. It was, he wrote, a brilliantly clear day of blue sky and blue sea.

Out over the bay, roughly above the small island of Xefina, which the Portuguese army was then using, something was hanging still in the air. He described the shape as two saucers or plates put together with their convex sides outward, seen edge on, so that it looked elongated and tapered at both ends. It was dark grey, solid, with clean edges and no fuzziness of cloud or smoke about it, no portholes, no protuberances. Its size was hard to judge, but he reached for the comparison of an ocean-going ship. It was perhaps a hundred and fifty or two hundred metres above the sea.

He had it for about thirty seconds. He was on the seaward side of the car and exclaimed, and pointed it out to his friend, who may or may not have caught it before the car passed behind the trees of a parking area and then the Clube Naval and the beach pavilion, which blocked the view. He told the driver not to stop. As the road climbed the embankment towards the Polana Hotel and the bay opened out again, the object was not where it had been. Then it flashed into view for a split second, climbing fast towards the south-west, straight over the city, and now, from underneath, it was a perfect circle. No sound over the car engine, no flame, no colour.

That is the whole of it. He was a diplomat, not a ufologist, and he wrote it plainly and put his name to it, and Hind printed it in the first issue of UFO Afrinews in 1988 with his name and city because he had offered them. The boatbuilder’s name is in there too. Neither man seems to have reported it at the time to anyone who would have written it down, which in colonial Lourenço Marques in 1968, with a war on in the north, was probably the sensible choice.

Xefina Grande is still a low, sandy island a few kilometres off the Costa do Sol, still with the ruins of the fort on it. The Marginal still rounds Ponta Vermelha with the bay open to the east, and on a clear afternoon it is still a very good place to look.