There were quite a few of them (Warwick Streets, that is). AFAICT there was a lot of renaming of London streets with the same name around the turn of the century, presumably to help avoid confusion between them for post, taxis, etc. I've come across the same thing in the past when researching things like family history. You can't necessarily rely on them being the same now as they were in the 1880s. I noticed last night when looking at the high res version that a WARWICK STREET S.E. street name sign is on the wall of the building on the corner. S.E. should have been a give-away (old fashioned shorthand for SE1). I was working mostly on gut instinct that it felt like somewhere in the area (I happen to work less than a couple of miles from there). It certainly wasn't Westminster.