Fitzrovia ("North Soho") is a small pocket of London which has, miraculously, escaped the destruction of wartime bombs, development and - most destructive of all - gentrification.
Waves of immigrants have swept through it leaving their distinctive sediments. The area round Fitzroy Square was, in the 19th century, loved by returned nabobs. Its air is still fragrant with curry by mid-morning. Eminent literary Bloomsberries (the sainted Virginia herself) occupied the grand houses of Fitzroy Square. Jewish refugees from the European pogroms took up residence in the seedier side streets, leaving a heritage of small shops. There are lugubrious pubs and mysterious mews - home to the knocking shops that advertise themselves in local phone boxes. Students from the nearby universities and teaching hospitals find it convenient (and fun) to live in Fitzrovia.
At the tube station end of Warren Street - along from Zack the Optometrist and the thriving 24-hours Defence Lawyer - is the Health Food Centre. It's a salubrious establishment, with an appetising line in fruit juice and veggie sandwiches. But its most profitable range of goods is advertised on sidewalk placards. "Natural Viagra! Herbal Aphrodisiacs! Restore Your Love Life! Tigra. Cobra. Action Tabs. Ashgawandha. Veromax."
The shop is run by subcontinentals; hence the Jungle Book motif. Shere Khan, one imagines, has no erectile dysfunction issues. A restored love life does not, however, come cheap. A pack of 60 Veromax pills costs £32.95. Even the "testosterone booster" ashwagandha ("Indian Miracle Herb!") will set you back a tenner a packet.
But, when all else wilts, hope springs eternal. I posted myself opposite the shop for an hour and saw at least five customers who were not, I suspect, in the market for papaya juice cocktails or mustard-and-cress sarnies.
There are, the internet informs one, some 50 topselling "Viagra [TM] alternatives". Most have come-and-get it names such as Boom, Viva, Tap (turn it on and stand back) and "Vivace - sexual enhancer for women".
Do these natural aphrodisiacs work? The Health Food Centre is 100m from UCL's world renowned department of pharmacology. I took my query there. "Not my field," said one eminent Fellow of the Royal Society ("Nor mine", I quickly added).
He made the shrewd point, however, that it was no one's commercial interest to do the clinical and field testing required to answer the question. If the results were negative, the herbal market (which, particularly in America, is enormous) would collapse. If positive, Big Pharma would lose its monopoly to a natural product they couldn't patent. As disastrous for the shareholders as a natural cure for Aids.
Given the growth of the herbal/natural market, such testing should take place since some of these products might be "downright dangerous". No one knows. The necessary rats had not been poisoned to find out. Like other scientists, he was suspicious of "the whole crackpot homoeopathy business" and despised the "dietary supplement loophole in the law" that enabled untested, and potentially potent products to be tried on the impotent.
He referred me to a colleague. "I would not call Viagra an aphrodisiac," this expert observed, "since as far as I know it does not increase libido but merely increases the strength and duration of an erection. Any aphrodisiac effect is likely to be secondary to removal of worry about potency. It works by inhibiting an enzyme called phosphodiesterase and the effect is to increase blood flow to the penis." (Somehow, I can't see that last sentence on a sidewalk placard).
It was, he thought "possible that there are naturally occurring materials in plants that either have a similar mechanism or increase blood flow by a different mechanism." Most likely, if such products put lead in the pencil, it was because they acted as placebos.
And "placebo", of course, means: "I give pleasure." Perfect. Trademark it now, Mr Pfizer, before Mr Wellcome or Mr Glaxo do.