"My professional charges are on a fixed scale," said Holmes coldly. "I do not very them, save when I remit them altogether."
-- "The Problem of Thor Bridge"
Now, that is obviously just not true!
Leaving aside little tips like the gold snuff with amethyst from the King of Bohemia (SCAN) and the emerald tie pin from the Queen of England (BRUC), Holmes pocketed large amounts of cash on numerous occasions.
In "The Adventure of the Beryl Coronet," he earns a 1000 pound reward. Even more impressively, in "The Adventure of the Priory School," Holmes neatly folds a check for 6,000 pounds.
How then to account for the assertion that his fees are fixed? For years I couldn't explain this bald-face lie to J. Neil Gibson, the Gold King. Recently re-reading a classic essay, however, I found a convincing explanation that I had forgotten. In "Nummi in Arca or The Fiscal Holmes," R.K. Leavitt writes:
First, he wanted to put the blustering purse-proud Yankee in his place, and second, he was at the moment calculating how much Gibson would stand for, and he was astute enough to lay the foundations for an unquestioning acceptance of the account he meant to render. In this case, at least, Holmes did not deceive his hearer out of mere sport.This perceive essay is collected in the invaluable 221B: Studies in Sherlock Holmes, edited by Vincent Starrett, where I read it as a lad, and also in The Grand Game: Volume One, edited by Laurie R. King and Leslie S. Klinger.