I had once, when travelling to Scotland by night, stayed awake to write some letters and post them at Crewe when the train would reach its first stop. I had thought then, as I sat looking at the platform after getting rid of my letters, how easy it would be to leave the train unobserved. The attendant stepped out to receive late-joining passengers and then went away on affairs of his own. There was a long wait at a quite deserted platform while luggage was loaded into the distant vans. If one had managed to travel so far unaccounted for, one could step off the train and no one would ever know that one had been on it.

That memory was the first of the two props for my inspiration.

The second was my possession of Charles Martin’s papers.

Charles Martin was my mechanic. He was the only European and the only technician (what an appropriately deplorable word!) ever employed by me. I engaged him for the least successful of my expeditions, the semi-mechanised one, because my Arabs (though learning rapidly, alas!) were not skilful with machinery. He was a repellent creature, interested in nothing but internal combustion and the avoidance of his share of camp duties, and I was not sorry when he died in mid-desert. We had by that time found the vehicles a liability rather than a help and had decided to abandon them, so Martin had already outlived his usefulness. (No, I had nothing to do with his death; Heaven in this instance did its own scavenging.) No one asked for his papers, and since the journey was from coast to coast we never returned to the town in which I had engaged him. His papers lay in my baggage, a matter of no interest to me or to anyone else, and came back to England with me.

I remembered them when it was necessary to silence the Kenrick youth. Kenrick looked not too unlike Charles Martin.

It was Kenrick’s plan to go back to his Carter-Paterson occupation in the East until such time as I should join him there, and we should then set out on our expedition together. He came to see me at Britt Lane very often, to discuss routes and plume himself on the prospect in front of him, and it amused me to see him sit there and babble his nonsense when I had so strange a translation prepared for him.

He had arranged to go to Paris by the night-ferry on the 3rd. He ‘collected’ ferries, it seemed. He would go many miles out of his way to be punted across a stream which he could have crossed by a bridge a few yards from where he was standing. The Dover ferry was to be his two-hundredth, I think. When he told me that he had booked a berth on the train-ferry I telephoned, as soon as he had gone, and booked a berth to Scoone in the name of Charles Martin for the same night.

When I next saw him I suggested that since I was going to Scotland on the same evening on which he was leaving for Paris, he should leave his luggage (he had only two suitcases) in the cloak-room at Victoria, dine early with me at Britt Lane, and see me off at Euston.

He was always delighted to fall in with any suggestion that I was moved to put to him, and he agreed, as I knew he would, to this. We dined, on a rice and cutlets and apricots dish that Mahmoud has taught Mrs Lucas to make (it needs long cooking so that the dish is impregnated with the flavour of the apricots) and Mahmoud drove us to Euston. At Euston I sent Kenrick to pick up my sleeper ticket while I went ahead. By the time Kenrick rejoined me I had found my compartment and was waiting on the platform for his arrival. If by chance he wondered why I was travelling as Charles Martin I had the excuse of my fame to account for an incognito. But he made no comment.

I felt that the gods were on my side when I saw that the attendant was Old Yughourt. You will not know Old Yughourt. He has never in the whole course of his career been known to take an interest in any passenger whatever, his chief object when on duty being to retire to his own unsavoury compartment at the earliest possible moment and go to sleep there.