“There was a pause then for an hour or more. About half-past ten the No. 4 lorry with your friend appeared coming along the lane outward bound. It was heavily loaded with firewood and I followed it along, going very slowly and bumping over the inequalities of the lane. When it got to a point about a hundred yards from the road, at, I afterwards found, an S curve which cut off the view in both directions, it stopped and the driver got down. I need not tell you that I watched him carefully and, Merriman, what do you, think I saw him do?”
“Change the number plate?” suggested Merriman with a smile.
“Change the number plate!” repeated Hilliard. “As I’m alive, that’s exactly what he did. First on one side and then on the other. He changed the 4 to a 1. He took the 1 plates out of his pocket and put the 4 plates back instead, and the whole thing just took a couple of seconds, as if the plates slipped in and out of a holder. Then he hopped up into his place again and started off. What do you think of that?”
“Goodness only knows,” Merriman returned slowly. “An extraordinary business.”
“Isn’t it? Well, that lorry went on out of sight. I waited there until after six, and four more passed. About eleven o’clock No. 6 with the clean-shaven driver passed out, loaded, so far as I could see, with firewood. That was the one that passed in empty at nine. Then there was a pause until half past two, when your friend returned with his lorry. It was empty this time, and it was still No. 1. But I’m blessed, Merriman, if he didn’t stop at the same place and change the number back to 4!”
“Lord!” said Merriman tersely, now almost as much interested as his friend.
“It only took a couple of seconds, and then the machine lumbered on towards the mill. I was pretty excited, I can tell you, but I decided to sit tight and await developments. The next thing was the return of No. 6 lorry and the clean-shaven driver. You remember it had started out loaded at about eleven. It came back empty shortly after the other, say about a quarter to three. It didn’t stop and there was no change made with its number. Then there was another pause. At half past three your friend came out again with another load. This time he was driving No. 1, and I waited to see him stop and change it. But he didn’t do either. Sailed away with the number remaining 1. Queer, isn’t it?”
Merriman nodded and Hilliard resumed.
“I stayed where I was, still watching, but I saw no more lorries. But I saw Miss Coburn pass about ten minutes later—at least I presume it was Miss Coburn. She was dressed in brown, and was walking smartly along the lane towards the road. In about an hour she passed back. Then about five minutes past five some workmen went by—evidently the day ends at five. I waited until the coast was clear, then went down to the lane and had a look round where the lorry had stopped and saw it was a double bend and therefore the most hidden point. I walked back through the wood to the bridge, picked up my taxi and got back here about half past seven.”
There was silence for some minutes after Hilliard ceased speaking, then Merriman asked: