Watson is a unreliable narrator. And he isn’t even ashamed of it.
Augustus Milverton, 1885-1888?
It is years since the incidents of which I speak took place, and yet it is with diffidence that I allude to them. For a long time, even with the utmost discretion and reticence, it would have been impossible to make the facts public; but now the principal person concerned is beyond the reach of human law, and with due suppression the story may be told in such fashion as to injure no one. It records an absolutely unique experience in the career both of Mr. Sherlock Holmes and of myself. The reader will excuse me if I conceal the date or any other fact by which he might trace the actual occurrence.
So Watson simply says that he will change any facts he deems necessary. Beautiful.
The Second Stain, 1888
If in telling the story I seem to be somewhat vague in certain details the public will readily understand that there is an excellent reason for my reticence.
It was, then, in a year, and even in a decade, that shall be nameless, that upon one Tuesday morning in autumn we found two visitors of European fame within the walls of our humble room in Baker Street.
“Somewhat vague”? If you read the second sentence, that is the understatement of the century.
A Scandal in Bohemia, 1889
“You may address me as the Count Von Kramm, a Bohemian nobleman. I understand that this gentleman, your friend, is a man of honour and discretion, whom I may trust with a matter of the most extreme importance. If not, I should much prefer to communicate with you alone.”
I rose to go, but Holmes caught me by the wrist and pushed me back into my chair. “It is both, or none,” said he. “You may say before this gentleman anything which you may say to me.”
The Count shrugged his broad shoulders. “Then I must begin,” said he, “by binding you both to absolute secrecy for two years, at the end of that time the matter will be of no importance. At present it is not too much to say that it is of such weight it may have an influence upon European history.”
“I promise,” said Holmes.
Here, it is not explicitly stated that Watson is veiling the facts, but the mere fact that he writes the story should tell the reader that he is changing enough to make the characters unrecognisable. It has been speculated that the nobleman in question was the Prince of Wales himself. (Would fit his character, by the way…)
The Three Students, 1895
It was in the year ‘95 that a combination of events, into which I need not enter, caused Mr. Sherlock Holmes and myself to spend some weeks in one of our great University towns, and it was during this time that the small but instructive adventure which I am about to relate befell us. It will be obvious that any details which would help the reader to exactly identify the college or the criminal would be injudicious and offensive. So painful a scandal may well be allowed to die out. With due discretion the incident itself may, however, be described, since it serves to illustrate some of those qualities for which my friend was remarkable. I will endeavour in my statement to avoid such terms as would serve to limit the events to any particular place, or give a clue as to the people concerned.
Here, Watson masks the truth for more personal reasons, and everybody is fine with it by now. The summarised content of this paragraph is “I essentially invented the following story, enjoy reading about my friend”.
The Illustrious Client, 1902
The client’s name is not even mentioned. Just that it is “illustrious”. (Also, the damsel in distress is called Violet, another sign that…something was changed by Watson (see TJLC and 1895)).
And in the Christmas Special? Well, in the trailer we have all seen how “reliable” Watson’s writing will turn out to be…
By the way, this works perfectly well on another level too: That Watson, the author, constantly lied is clearly canon. “Our” writers, Mofftisson, have to lie as shamelessly and as much to follow the “original”, canonical attitude to lying – in both cases to veil Johnlock (albeit with similar levels of success).