He pored over the newer letters, then went back and forth between them and the originals.

“There’s a passage of time involved between the exemplars and the subjects, of course,” he said. “But one’s handwriting from one’s adolescence will not change overmuch by the time one reaches one’s thirties, barring injuries or other infirmities. She had none?”

“Nothing that would affect her handwriting, as far as we know,” said Iris.

“There are enough capital letters in both sets to compare, as well as all the little connections between letter pairs, which is where the giveaways can occur.”

“Have you found any?” asked Gwen.

“I have not,” he pronounced. “These are dated from 1918 and 1919. The paper and ink are completely consistent with that period and location. The handwriting is the same. If I were called on to testify in a court of law—and God help the side that calls me, with my record—my expert opinion would be that these are the real article.”

“They are?” exclaimed Gwen in dismay.

“Yes. That is not happy news, I take it?”

“We had a small wager on the outcome,” said Iris, smiling in triumph. “Now, we have a second set. No exemplars this time, so just your conclusion on time and place again.”

Gwen handed him two of the blue onionskin letters from “C.” Jimmy repeated his taste and smell tests, then peeled off one glove and trailed the tips of his fingers lightly over the papers.

“Also Swiss, same period,” he said. “And may I venture one psychological observation?”

“Certainly.”

“This is the sort of stationery one buys when one doesn’t wish to be connected to it. If, as I gather from the small sample you’ve provided me, your fellow ‘C.’ is not using his personal stationery, then I would suppose that the remainder of this correspondence is of an illicit nature.”

“Which will remain confidential,” said Iris.

“Of course,” he said. “I am scandalised that you even feel the need to say that, Sparks.”

“My apologies, Jimmy,” she said, patting his hand. “I do hope that your sense of honour is not so offended as to refuse a small fee for your services?”

“Happily, it is not,” he said. “Do you need an invoice?”

“Strangely enough, we do.”

“How shall I make it out?”

“‘For expert services,’” said Iris. “The client won’t want to know more than that.”

“They rarely do,” he said, writing it out and handing it to her along with the letters. “Don’t forget these. Unless you’d like to make a quick deal on them—as I said, there’s a market for them.”

“We know,” said Gwen. “At the moment, it’s booming.”

Gwen was gloomy when they left the shop.

“Cheer up,” said Iris, noticing.

“I was counting on him backing me up,” said Gwen.

“If it’s any consolation, I still think you’re right,” said Iris.

“And what was that about a wager?” asked Gwen. “We never said anything about it.”

“I didn’t want you to go any further on the topic,” said Iris. “You were so surprised by his answer. I was worried you might let something slip.”