In May 1987, when I was still working with a anglo-German truck company, a driver took me to London and there I found myself  exploring, testing my knowledge of English.  Shortly afterwards, I jotted some notes about my trip and used them later for my novel : Souvenir of Germany.  My protagonist Tatiana Arnold takes exactly the same trip, albeit in December 1986 and this is what she sees in London: 

Friday the 19th,   while Tatiana was having breakfast the next morning,  - toast, orange marmalade and black tea, it was very cold outside. Despite the winter showers, she had planned to explore the Sherlock Holmes Museum after visiting HMV on Oxford Street, the world’s largest record store. All her favourites were there: Joni Mitchell, Bob Dylan, America, Ralph McTell, Gerry Rafferty. She bought a CD with Gerry Rafferty’s singles "Baker Street" and Ralph McTell’s "Streets of London" as well as a CD of Christmas carols. She told herself that she had made a very good choice and was eager to listen to her music on her CD player at home. For lunch she went to the Selfridges Café and ordered a quiche and a melon and sweet-corn salad. ...

Then she explored Baker Street - that’s where the legendary fictional detective Sherlock Holmes lived. She was a fan and never missed any episode of the TV show with Jeremy Brett. To her great disappointment, only an oval sign paid tribute to Sherlock Holmes because in 221b there was an administrative building. The staff of the eponymous hotel informed him that in the past there had been a museum but that it had closed due to bankruptcy two years earlier.

a new privately run  Sherlock Holmes museum  opened in 1990 and is situated in Baker Street and bears  the number 221B by permission of the City of Westminister although it lies between numbers 237 and 241, near the north end of Baker Street in central London close to Regent Park. Of course I visited that one as well, but that's another story.

Souvenir of Germany - Chapter 11