“I remember Commander Blair in the War,” said the Prime Minister quietly. “Bellows Blair, they called him. He did excellent expert work. Some new scheme with dirigible balloons. But I was only going to ask Mr. Oates whether he happens to know where Welkin Castle is.” “Must be somewhere near here,” suggested Normantowers, “as the letters seem to come by hand.” “Well, I don’t know,” said Enoch Oates doubtfully. “I know a man living in Ely, who had one of those letters delivered by hand. And I know another near Land’s End who thought the letter must have come from somebody living near. As you say, they all seem to come by hand.” “By what hand?” asked the Prime Minister, with a queer, grim expression. “Mr. Oates,” said Lord Normantowers firmly, “where _is_ Welkin Castle?” “Why, it’s everywhere, in a manner of speaking,” said Mr. Oates reflectively. “It’s anywhere, anyhow. Gee--!” he broke off suddenly: “Why, as a matter of fact, it’s here!” “Ah,” said the Prime Minister quietly, “I thought we should see something if we watched here long enough! You didn’t think I kept you hanging about here only to ask Mr. Oates questions that I knew the answer to.” “What do you mean? Thought we would see what?” “Where the unstamped letters come from,” replied Lord Eden. Luminous and enormous, there heaved up above the garden trees something that looked at first like a coloured cloud; it was flushed with light such as lies on clouds opposite the sunset, a light at once warm and wan; and it shone like an opaque flame. But as it came closer it grew more and more incredible. It took on solid proportions and perspective, as if a cloud could brush and crush the dark tree-tops. It was something never seen before in the sky; it was a cubist cloud. Men gazing at such a sunset cloudland often imagine they see castles and cities of an almost uncanny completeness. But there would be a possible point of completeness at which they would cry aloud, or perhaps shriek aloud, as at a sign in heaven; and that completeness had come. The big luminous object that sailed above the garden was outlined in battlements and turrets like a fairy castle; but with an architectural exactitude impossible in any cloudland. With the very look of it a phrase and a proverb leapt into the mind. “There, my lord!” cried Oates, suddenly lifting his nasal and drawling voice and pointing, “there’s that dream you told me about. There’s your castle in the air.” As the shadow of the flying thing travelled over the sun-lit lawn, they looked up and saw for the first time that the lower part of the edifice hung downwards like the car of a great balloon. They remembered the aeronautical tricks of Commander Blair and Captain Pierce and the model of the monstrous pig. As it passed over the table a white speck detached itself and dropped from the car. It was a letter.