“What fantastic nonsense is this!” cried Colonel Reid in a tone of disbelief.

“It is the truth.”

“How can you know?” demanded the colonel. “What possible reason can you have for supposing such a thing?”

“Because the forger has made a mistake. I have seen the note, and I have seen an exercise book of poems that Sarah Dickens had written, and the handwriting, although very similar, is not the same.”

“Everyone else considers the note to be in the girl’s own hand.”

“Everyone else is wrong.”

“Why should you be the only one to detect this difference?”

“Because I am the only one who has examined the writing with sufficient care.”

“But even her own family accepted that the note was genuine, and no one could have been more familiar with her hand than they were.”

“Well, of course, the two samples of handwriting are very similar. If you were writing a note, but wished it to appear to be the work of another, you would obviously take great pains to make the letters appear as much like those of the other person as possible. There would be little point in attempting the task otherwise. That the note found by the Willow Pool was taken to be the work of Sarah Dickens is thus no more than one would expect, under the circumstances. The dead girl’s hand was neat and regular. She had evidently learnt her handwriting lessons at school very well. Her style did not deviate to any significant extent from the copybook style she had been taught, and displayed few of those idiosyncrasies to which an older person’s hand is prone. This would have made it uncommonly easy to imitate, and it cannot be denied that the murderer – for the murderer’s hand it must be – made a good job of it. However, he made a little slip. He missed the one variation that Sarah Dickens had introduced into her hand – the formation of the letter ‘f’. There are, as I recall, three instances of this letter in the note that was found, and not one of them is formed in the same way as those in her book of poetry. It was almost the very first thing that struck me when I saw the two samples of writing.”

“But surely everyone’s hand varies a little, each time pen is put to paper,” protested Admiral Blythe-Headley in a sceptical tone.

“That is true, but such trivial and transient variations are not important. There are certain letters, however, those, generally speaking, which are more complex in structure, which are especially liable to idiosyncratic formation, and are thus of particular importance in identifying the author of a piece of writing. Of these letters, although ‘b’ and ‘g’ may also be of significance, ‘f’ is generally the most reliable guide.”

“That is amazing!” cried Captain Ranworth.

“On the contrary,” returned Holmes, “it is perfectly elementary; but like everything else in this woeful case, it is an issue that was overlooked or misjudged by those whose duty it was to establish the truth of the matter. The girl did not write the note, and thus it is of no direct relevance to her death. It has, however, been of immense importance to the case as a whole.”

“What on earth do you mean?” demanded Admiral Blythe-Headley in a tone of bewilderment. “Stop speaking in riddles, man!”

“I mean simply this,” replied Holmes in a calm voice, “that everyone at the inquest was at very great pains to declare that the note in question did not constitute a suicide note. It is perfectly clear, nevertheless, that it was the existence of the note that planted the idea of suicide so firmly in the general mind, conjuring up so vividly as it did the picture of a sad and forlorn young lady, who, it appeared, had been pining for a lost love. Had there been no note, perhaps the people of this parish would not have been so blind as to what really occurred that afternoon at the Willow Pool. The note also served, by its use of the phrase ‘you have gone away and left me’ to confirm what many had suspected concerning Captain Reid: that he had at least been trifling with Sarah Dickens, and had perhaps seriously abused her affection, for at the time of the girl’s death, of course, when the note was discovered, Reid had indeed ‘gone away’ less than two weeks previously. In sum, the note was one of the very foundation stones of the terrible obloquy that has been heaped so unjustifiably upon the head of this unfortunate young man.”

There was silence for a moment in the room, and it was evident that Holmes’s careful and detailed exposition of the case had made a very profound impression upon everyone there.

“I can hardly credit my ears,” said Admiral Blythe-Headley at length. “You have argued your case very well, young man, but I am still not entirely convinced. What about our garden bench? You will be telling us next that John Reid was not responsible for that, either!”

“That is correct. He had nothing to do with it.”

“What! Of course he did!” the admiral retorted. “It could be no other but he! Why, he was seen to be loitering in the garden pavilion earlier in the afternoon! We certainly had no other visitors that day.”

“It was not a visitor that caused the damage.”

“One moment!” Ranworth interrupted. “Where has Reid himself vanished to?”

I turned to see. The last time I had glanced in his direction, Captain Reid had been standing by the open door of the room. Now he was nowhere to be seen; he had evidently slipped away while the attention of everyone else had been upon Sherlock Holmes. There were general expressions of surprise and perplexity; Holmes alone appearing unperturbed by his client’s disappearance.

“He will be back in a few moments,” was his only remark.

Captain Ranworth appeared momentarily confused, but at length he spoke. “I was about to remark,” said he, “that it is a great misfortune that three years have passed since these events of which Mr Holmes has been speaking. I, for one, am sure that all that you say is correct, Mr Holmes; but now, after so much time has elapsed, there must be very little likelihood of our ever discovering who was really responsible for the death of Sarah Dickens.”

“On the contrary,” returned Holmes in a firm voice, “I am confident that I could very quickly lay my hand upon the man responsible.” He turned to Colonel Reid. “You expressed some doubt earlier when I stated that your son returned home from India perfectly ignorant of what was alleged against him.”

The colonel nodded his head vigorously. “I have kept my peace until now,” said he in a firm voice, “and have allowed you to state your case at some length. But you must know that everything you say is vitiated by one simple consideration: if my son is as innocent of any involvement in this affair as you claim, why, then, did he not take the opportunity I offered him to deny the allegations?”

“You wrote to him on the matter when he was in India?”

“Yes, of course I did. I described to him the rumours that were circulating following the death of that girl, and asked him to assure me that they were utterly false. He did not respond to my request. I then wrote to him again, stating that if he did not clearly deny the rumours to me, I would take it that he could not, because they were true. Again, he did not respond. Only one conclusion was possible.”

“Colonel Reid,” said Holmes, “your son never received the letters you sent. That is why he did not respond to the rumours and accusations.”

“There you are quite wrong, Mr Holmes,” returned the other. “There is no doubt whatever that he received them, for in the letters that he wrote to me he responded to one or two other trivial matters that I had mentioned in my letters, but not to my questions about Sarah Dickens.”

“I say again,” Holmes persisted, “that your son never received the letters you wrote to him. They were intercepted by someone else, someone who did not wish your son to have the opportunity to deny the rumours and thus clear his name.”