Through a five-inch-wide crack in the floor slab, Rigby shone a torch to see that beneath it was a hollow chamber of indeterminate size, partially collapsed. As he angled the light this way and that his heart leapt at the unmistakable glimmer of gold from within. Abdul was poised at his shoulder, peering intently through the crack and seeing what he saw. The Afghan’s normally laconic expression filled with excitement.

Now, their tiredness completely forgotten, they set about widening the crack to get at what was inside. ‘Gently, gently!’ Rigby said over and over. ‘Don’t do any more damage than you have to!’ Using crowbars they carefully worked at the gap until it was possible for the most slightly built of them, a fourteen-year-old boy called Safi, to slip through and drop down into the hollow space below. Rigby was worried that the chamber might collapse and bury the boy alive.

The casket was much too heavy for young Safi to bring up, so they had to lower a rope with a sling attached and haul it up through the gap, swaying and swinging precariously as it inched upwards. Rigby was hoarse from repeatedly urging caution. At last, the casket was through the gap, grabbed by eager hands that set the swinging golden oblong box carefully down on the ground. At the same moment there was a cry from inside the chamber, and for a heart-stopping instant Rigby thought something terrible must have happened to the boy. But no, Safi had found another casket!

The second casket was soon joined by a third, then a fourth, all laid out in a row. By the light of torches and lanterns Rigby knelt on the ground and used a brush to wipe away the filth of millennia to reveal the royal seal of Alexander the Great cast in gold on the side of the first casket.

This was it. The final, irrefutable proof he’d hoped to find. He bowed his head, almost weeping with emotion as thousands of years of history seemed to flash in front of him. He murmured, ‘My God. We found it. We found it.’

The men were hopping from foot to foot with excitement. Rigby took out a penknife and gently, oh so gently, prised open the seal of the first casket lid. As the lid came up, he breathed in the air that had been trapped inside for some 2,300 years.