That street featured in one of the newer Sherlock Holmes episodes.

 

I never knew that, which is odd because in my early teens I used to cycle down that road every day, either to deliver some chops or steak to houses around there, but certainly to cycle down the road on my way home afterwards.

 

There's plenty of interest around the London Underground of this 'did you know?' sort. A favourite of mine relating to my expensive hobby - high fidelity music reproduction - was the sound of a tube train to be heard in some recordings made in Kingsway Hall, which the now closed Aldwych branch ran beneath. A little hushed subterranean bass, which definitely wasn't in the composer's score; just as when it was a live concert venue.

 

Hi Bobcat / All,
Leincester Gardens Terrace is definitely a very very unusual "fake" building facade, but there are also many others around, such as the below in Knightsbridge, being a 6ft wide fake building block / flats -

Over the years we looked at a number of project's near to some of these "fake" facades; the Leincester Terrace is also Listed to complicate things somewhat too.
As 34C has also mentioned in the post above, sometimes "unknown / declared" railways or infrastructure near to or below buildings, can come as quite a surprise; the discovery of the "Secret" Post Office Railway under the ITN building, after all the 30m deep piling had been completed & the basement structure built, came as quite a surprise for sure ! Just how did we miss it ..............................
Must say these sort of "un-noticed" buildings / structures / facades are always fascinating to say the least.
Cheers as always, Norm