Success is meant to smell sweet, but 150 years ago, as London ballooned to accommodate 2.5 million souls, becoming the largest city the world had ever seen, it quite frankly stank.

In this hub of a glorious, steam-driven empire, the average life expectancy of the city's poorest was only 16, and the cellars of even the better off were often full of excrement. Still, the muck signaled a business opportunity to the 100,000 or so toshers (copper salvagers), mudlarks and bone-pickers who crammed the city's margins, scavenging its corpses or sifting through its effluvia on the banks...