Oh yes, this friend is a barrister. Denise specialises in criminal law and has one of those commanding voices that people accustomed to dispensing authority develop. It will end up passing sentence one day.

She then said, half seriously, that the real crime was not availability of cocaine, but that it was poor-quality and often mixed with other substances. “It was much better a few years ago,” she explained. “Now I think they put in that other thing, ‘speed’, which makes you hyper and twitchy and leaves you feeling dreadful. It’s still roughly £50 a gram, about the same as 1997.”

“I won’t mention your name,” I volunteered, but without being asked. “Oh yeah, don’t,” she said absently. “Won’t go down well in Chambers. Curtains, probably. But lots of solicitors and barristers use it.”

Worryingly, these days cocaine no longer excites passions or raises moral indignation. Nobody feels much need to disguise their use of it, which is why it is simple to find out where to buy some.

If I can discover three places, a couple of users and two dealers in less than 40 minutes, and I don’t take drugs, then Sir Ian Blair, the new Metropolitan Police Commissioner, should find it easy to deal with the “weekend” drug users whom he intends to target. But I suspect that the success will be superficial.

The image that springs to mind is of a bear (the police) standing over a fast-flowing Alaskan river (London) and lazily plucking from the seething mass of salmon (users). The bear gets lots of fish, but there are so many that most of them will escape. And they’ll be back.

Few people I know would light a cigarette at a drinks party these days, yet many would not hesitate to fire up a joint, and the streets often stink of burning marijuana. A latter-day Dick Whittington would be stoned long before reaching the City.

Though cocaine use may still be confined to the kitchen or the toilet, this is not to do with embarrassment, but the inelegant, tricky, snorted ingestion that requires flat surfaces.

Twenty years ago coke use was at least described as a vice. Not now. It is far too ordinary: neither reviled, exclusive nor carrying social stigma. Despite being a non-participant, I have never witnessed as much undisguised ingestion as there is today. There is clearly neither guilt nor anger, shame or embarrassment. It is not edgy and out there, but established and in here. This is despite the fact that cocaine remains a dangerous and highly addictive drug — and, of course, highly illegal.

My friend Tamsin (I’ve changed her name, too, but my choice suits) took no encouraging before telling me about going to her first “white party”. She is 34. “It was at a big house in Earls Court just after Christmas, and the host went into the hall. He came back with this huge mirror, one of those hotel ones. It took five of them to lift it. Anyway, they brought it into the dining room and just laid it across the table, which seated 12. I said, ‘What are you doing?’ He just said, ‘You’ll see’.”

The attentive host then laid out lines of cocaine for his guests to snort through rolled banknotes. “I’m not joking, Toby; he told me this was our starter, main course and dessert,” Tamsin said. They all got stuck in.

But not Tamsin, a non-user, although the pressure was high. “Men always say, ‘You have to try it, then we’ll both be experiencing the same thing’.” It was doubly hard that night. She had to help herself to cheese and biscuits from the kitchen to get anywhere near a meal. “It’s really boring watching other people get wasted.”