The Criterion Bar is the bar in which Dr. John Watson met Stamford and was thus introduced to Sherlock Holmes.

It was also a frequent meeting place for inverts (gay) men in the Victorian era.

‘A New City of Friends’: London and Homosexuality in the 1890s

Matt Cook

History Workshop Journal, Volume 56, Issue 1, 1 October 2003, Pages 33–58,
https://doi.org/10.1093/hwj/56.1.33

Published:

01 October 2003

"..Ives noted that the Criterion Bar on Piccadilly Circus was 'a great center for inverts' until it closed in 1905 ."

The Inverted City: London and the Constitution of Homosexuality 1885-1914
Matt Cook
https://qmro.qmul.ac.uk/jspui/handle/123456789/1620

Mentioned in the quoted article above is George Cecil Ives, who was an LGBT advocate in the Victorian Era, and lead the secret society 'Order of Chaeronea'...
... He was also a friend and cricket teammate to Sir. Arthur Conan Doyle.

There are many bars in England and surely Sir. Arthur Conan Doyle could have chosen any one to have Dr. Watson have that fateful meeting with Stamford... of all the bars that could have been used (or invented), he chose one which was popularly used by gay men.