He did continue it. Before long Perry excused himself and fled. I may have been prejudiced, but I enjoyed Schmidt’s commentary a lot more than I had Perry’s. For one thing, Schmidt isn’t afraid of expressing his emotional reactions. Some of the details – a group of blind musicians, a pair of vibrant, prancing horses – moved him so much he actually stopped talking, which was more than Perry had done.

After we had seen the tombs we all gathered around Feisal and one of his flunkies for a spot of refreshment. Drinking lots of liquids was a necessity in that climate; dehydration had felled a number of ignorant tourists. As I had come to expect from Galactic Tours, we were offered a variety of beverages as well as water, plus cookies and biscuits.

Schmidt was so happy. Friends, antiquities, and now food. He had been crooning to himself, and after we had collected our lemonade and cookies he burst into song. It is easier to let Schmidt sing than try to talk him out of singing, so I gritted my teeth and let him go on. ‘“Frankie and Johnny waren Liebende,”’ he bellowed. ‘“Mein Gott, wie verstanden sie sich auf die Liebe!”’

Several of the more nervous passengers jumped spasmodically, and John, standing nearby, actually reeled back a few steps. Schmidt took his pained stare for fascinated interest. ‘It is old American Volk musik,’ he explained. ‘The gnädige Frau from Hamburg has told me what a fine musician you are, Sssss . . . Herr Tregarth; no doubt you are familiar with that song?’

John shook his head. For once, he appeared to be incapable of speech.

‘Oh, but it is very well known. In English it goes, “Frankie und Johnny were lovers, Oh, lordie – ”’

‘Ah, yes.’ John blinked.

‘It is a most interessante variety of music,’ Schmidt explained. ‘Songs of the country and of the Wild West, blues and bluegrass . . . These are not the same, you understand; they have different roots.’

‘Bluegrass,’ John repeated blankly.

‘Many are deeply and touchingly full of religion. Have you heard the one about the crash on the highway, when whisky and blood mixed together?’

John edged closer. I had seen the same look on the face of a cat when a small energetic child cornered it – horrified disbelief mingled with unwilling curiosity. ‘Fascinating. Tell me more, Herr Schmidt.’

I went quickly away. Not quickly enough, alas, to miss the next verse.

Eventually we retraced our steps to the waiting trailer, which was to take us to the next stop, the ruins of the Northern City. Schmidt caught up with me there, and Perry, who had been edging towards me, veered away. Feisal, counting heads, called to the stragglers to hurry up and urged the rest of us to take our places.

Schmidt gave me a hand up, which I accepted, and then turned to Mary. She was alone for once, and her anxious gaze was fixed on the upward path.