Victorian sexuality is often considered synonymous with prudishness, conjuring images of covered-up piano legs and dark ankle-length skirts. Historian Matthew Green uncovers a quite different scene in the sordid story of Holywell St, 19th-century London's epicentre of erotica and smut.

At the eastern end of the Strand, opposite the Royal Courts of Justice, William Gladstone stands atop a plinth. Four times Queen Victoria’s Prime Minister, this eminent, emblematic Victorian is flanked by four female effigies testifying to the virtues of education, inspiration, courage, and brotherhood. Gladstone himself looks stately and solemn, as is fitting, but also mildly outraged, all clenched fists and frowns.

Well might he: he’s staring straight down what was, in his day, variously described as “a foul sink of iniquity”, “a place where dirt and darkness meet and make mortal compact” and, in the words of the Times, “the most vile street in the civilized world”. This was Holywell Street, the meridian of London’s booming pornography trade and, throughout the century, a byword for the dirty book trade long before Soho.