This is the Henry Heath Hat Factory, a fragment of the old artisan Soho jammed right up against Oxford Street:
What's shown is the back; the front was presumably a shop even in Victorian times. The building, according to listing records, dates from the late 1880s, but the address dates back further than that. There's a pamphlet in the British Library's Evanion Collection of printed ephemera that was handed out at the 1884 International Health Exhibition in South Kensington - they had a demonstration there - and gives the firm's address as "Ye Hatterie", Oxford Street, "as in the reign of King George the Fourth".
The pamphlet is marvellous. It boasts of Henry Heath's contribution to "rational dress" (a "soft-fitting" riding hat for ladies, as recommended by the coursing correspondent of The Field) and his warrant as "Hat Manufacturer to King Alphonso and the Royal Court of Spain".
But the reason I wanted to write about this is because of the letters themselves, plain cast-iron-looking Victorian sans forms that are constantly struggling to turn back into something more complicated. Look at the crossbars of the "H" and "A" in "HAT":
You get the same effect on "Oxford Street". It's trying to be simple, but serifs keep breaking out - on the "r"s, on the "S", on the "t"...
As you'd expect, the building is now full of "creative" "industry" offices. I hope some of the occupants are sufficiently geeky about lettering to enjoy it.