I don't know if this is what the question setter is after, but from the article linked to below -
"Speedy’s Cafe, the sandwich emporium frequented by Holmes and Watson in the series, is a real café on Gower Street, near Euston – the BBC’s stand-in for 221b Baker Street. (In the Sherlock pilot it was run by Una Stubbs’s character and named Mrs Hudson’s Snax n' Sarnies, but that idea was swiftly dropped.)..."
http://tinyurl.com/y83hu28b