They also use carbonate of soda, fuller's earth, and pipe clay for the brilliant robes of election candidates. But the pristine togas of our magnificent Empire are effectively bleached with urine, obtained from the public latrines. The Emperor Vespasian, never slow to light on brisk new ways of squeezing out cash, had slapped a tax on this ancient trade in human waste. Lenia paid the tax, though on principle she increased her supply for nothing whenever she could.

The woman I had been telling the story to commented, in her cool way, "I suppose in the salad season, when everyone's eating beetroot, half the togas in the Forum are a delicate hue of pink? Do they rinse it out?" she enquired.

I shrugged in a deliberately vague way. I would have skipped this unsavoury detail but as it turned out eventually, Lenia's bleach vat was critical to the tale.

Since I lived six floors up in a block that was no better equipped than any other slum in Rome, Lenia's bucket had long been my welcome friend.

Lenia offered my visitor, not unkindly, "Girlies go behind the carding rails, dear."

"Lenia, don't embarrass my dainty client!" I was blushing on her behalf.

"Actually I left home rather suddenly."

Dainty but desperate, my client shot behind the rods where the dried clothes were hung on poles through the shoulders to be scratched down with teasels to bring up the nap. While I waited, I topped up my usual bucket and talked to Lenia about the weather. As one does.

After five minutes I ran out of weather.

"Get lost, Falco!" a carding-girl greeted me as I peered around the rails. No sign of my client.

Had she been less attractive, I might have let her go. She was extremely attractive and I saw no reason to part with that sort of innocence to anybody else. Cursing now, I barged past the giant screw clothes-presses and out to the laundry yard.

There was a furnace heating the well water used in the wash. There were garments spread over wicker frames above braziers of burning sulphur, which through some mysterious chemistry smokes in additional whiteness. There were several youths scoffing at my fury, and there was a dreadful smell. There was no client. I hopped over a handcart and set off fast down the lane.