SMILE. YOU’RE ON candid camera. And this is probably not a joke. There are A LOT of cameras around these days, as the not-so-slick assassins who killed a Palestinian leader found out last week.

Surveillance technology will eventually create crime-free societies, says Ali Hasan Cemendtaur, a Pakistan-born writer. "After the incident of a crime, we play back the cameras, and interpret the barcode-reader archive, to see what really happened. There is no getting away with crime in that society," he says. But he warns that the system would only work in a fully democratic, multi-party community. So scratch most places in Asia off that list.

I was peddling this theory in the bar when a Londoner pointed out that Mr Cemendtaur’s imagined camera-dominated society already exists. There are now more than 4.2 million surveillance cameras in the UK. "A guy can no longer scratch himself in London because there are an average of three high definition cameras looking at you, one doing a medium-close up, one focused on your scratching finger and the other on your trousers," he said. It’s highly inconvenient. Every time he wants to scratch himself, he has to take the Eurostar train to Paris.

Yet more than 97 per cent of crimes solved in the UK are unraveled by old-fashioned police work rather than cameras, he said. A study by the Liberal Democrats concluded: "Police are no more likely to catch offenders in areas with hundreds of cameras than in those with hardly any."

Here’s a case which shows why. An armed raider recently turned up at a bank in Kirchheim, Austria, ready to rob it. But it was early closing day. Staff were inside having a training session. Furious, he banged on the locked doors with his gun, before realizing that this was a really stupid thing to do. He fled. The video surveillance caught an image of him, but he was wearing a full-face mask, so all they got was a picture of a Barack Obama mask. The really funny part of the story is that the burglar actually WAS Barack Obama, trying to solve the US debt crisis. That’s my theory, anyway.

I remained undecided about whether technology could create a crime-free society until I got an email from a reader in the US. He said that while cameras were not as helpful as hoped, other forms of technology DID work. He told me about a guy in Milwaukee whose mobile phone was stolen recently. The victim simply went to the nearest computer and asked the phone to tell him where it was. It did. It even sent a photo of the thief’s home. He gave the information to police. Officers went to the address in the town of Oak Creek. Police Chief Tom Bauer arrested a man who confessed to six thefts.

Of course, this phone application, called MobileMe, can be used for non-crimes as well. You can contact your spouse’s phone by computer. "Hello phone, please tell me where my husband is and send me a photo, too, showing his exact location." Click. I foresee a rise in another sort of crime: battered husbands.