The opening lines of A Study in Scarlet are rich with details about Dr. Watson's past. His medical degree, his army service, even his injury. He recalls how he came to London without knowing anyone in the city and proceeded to blow through his cash reserves.
Just how far could one get on 11s. 6p. per day in 1881? And how fortunate we are that Watson couldn't keep to his budget. For his cash situation is what required him to find a flatmate...
Links
The Man Who Created Sherlock Holmes: the Life and Times of Sir Arthur Conan Doyle by Andrew Lycett
Teller of Tales: The Life of Arthur Conan Doyle by Daniel Shashower
2 - Watson in the City