The real 221B Baker Street in London isn't where you would think. It's actually between 237 and 241, where the address should be 239 Baker Street. A trick by Sherlock to keep Lestrade from finding his apartment, perhaps?
At the time the original Holmes stories were published, Sir Authur Conan Doyle chose the number "221" because the addresses on Baker Street in London didn't actually go that high. But the street was later extended, and for years the financial institution Abbey National answered letters addressed to Sherlock Holmes at 221B Baker Street. Eventually the Abbey National moved out, and the number was bestowed upon The Sherlock Holmes Museum in another building down the street, located between 237 and 241 Baker Street. And that's how it came to be that 221B Baker Street is a real Sherlock Holmes museum, albeit one situated where "239 Baker Street" ought to be.
Heather navy t-shirt in 60% cotton / 40% polyester shows the doorway of 221B Baker Street from the BBC's Sherlock
(which is, presumably, actually at
221B Baker Street in the show canon) against the background of the Union Jack. Machine wash cold. Tumble dry low. Imported
Timmy and the TG Staff think you'll like...