“Well,” said French. “Then did he?” Illingworth looked his question and French went on: “I’m looking to you for proof of the theory. First, do these magnetos carry a number? If so, is there a record of the number fitted to each car? If so, what was the number supplied with Mr. Berlyn’s car? Next, is that the number that came in for repair? Next, was there a magneto of that type ordered separately recently, and if so, by whom?” “Steady on, Mr. French,” Mr. Illingworth laughed. “What do you take me for? I’m not a detective. Now let’s go over that again, one thing at a time. Magnetos carry a number, yes, and we have a note of the numbers supplied to the different car manufacturers. They can tell you the number of the magneto they put on any given car. What car are you interested in?” “A fifteen-twenty four-seater Mercury touring car, number thirty-seven thousand and sixteen, supplied through Makepeace to a Mr. Berlyn of Ashburton.” “Right. I’ll ring up the Mercury people now.” Mr. Illingworth was indefatigable in his enquiries, but he was not prepared for the state of delighted enthusiasm into which his results threw French. “That’s got it,” the latter cried, eagerly. “A long shot, but a bull’s-eye! I have to thank you for it, Mr. Illingworth, and you don’t know how grateful I am.” The first fact was not encouraging. The magneto which had been supplied originally with Mr. Berlyn’s car was the same that had been sent in by Makepeace with the short-circuited winding. So far, therefore, the breakdown might have been genuine enough. But it was the second item which had so transported French. A precisely similar magneto had been sold as a spare about a month earlier and under circumstances which left no doubt as to the motive. It had been ordered by a Mr. Henry Armstrong, in a typewritten letter headed “The Westcliff Hotel, Bristol,” and it was to be sent to the parcels office at St. David’s Station, Exeter, marked, “To be kept till called for.” The letter was being sent over by hand, and when French received it a few minutes later he saw that it had been typed by the same machine as that ordering the duplicator. “That’s fine, Mr. Illingworth,” he repeated in high delight. “That’s one of my major difficulties overcome. I just want you to tell me one other thing. How long would it take to change the magneto—out in the country on a dark night?” “It’s a half-hour’s job for a skilled man. The actual lifting in and out of the machine is easy, but the setting is the trouble. The contact-breaker, as I’m sure you know, has to be set so as to give the spark at the right point in the engine cycle. That takes a bit of time.” “I follow that. But is there no way that the adjustable parts could be set beforehand to save that time?” “That’s right. They could be marked and everything set to the marks. That would speed things up.” “By how much, should you say?” “With everything marked, a man could do the whole thing in fifteen minutes.”