He was a perfectly credible character: bespectacled, reasonably well dressed, somewhere in his early 50s. He sidled up to me as I struggled with my bag having stepped out of East Finchley underground station.
"I'm terribly sorry, I really don't know how to put this." He looked flustered. "I've just visited one of my clients; I'm a psychotherapist, and I've just had my wallet stolen." I immediately offered my sympathy, but he wasn't looking for sympathy. "I have to get to Berkhamsted and I need £15. I hate to ask you this, but can you possibly lend me the fare? I'm really sorry."
At this point, alarm bells began to ring in the back of my brain. I stammered something incomprehensible.
"Look, I know what you're thinking, but let me assure you..." He paused. Then came his killer line, his unique selling proposition: "Do you know Lawrence at the bakery on Market Place?" As a reasonably loyal customer of said bakery, I did know Lawrence well enough to know his name. He's a genial and affable sort; the kind of person you wouldn't think twice about helping. "I'm his brother", he exclaimed.
It was, of course, the most brilliant line. How on earth could I ever let myself not help Lawrence's brother in his hour of need? I wouldn't be able to live with myself. I envisaged Lawrence telling me about his poor brother getting mugged in this leafy London suburb, his failure to elicit the help of a passer-by, and my feeble attempt at feigning surprise and disgust.
I pulled £15 out of my wallet and thrust it into his palm. "Please let me have your mobile number and I'll arrange to pay you back", he said, and pulled an old-fashioned mobile from his pocket and dialled my number into the phone.
As soon as he'd turned in the direction of the station I knew instinctively that I'd never hear from this stranger ever again. I knew in my heart of hearts that I'd been had, been diddled, and for a moment I felt stupid and gullible. But then again, had I refused, I'd have felt mean spirited, callous and inhuman. But by the time I returned home I had put the whole thing out of my mind.
It wasn't until a few weeks later, while on the phone to my brother, that I was reminded of the incident. "A strange thing happened to me on the way home the other day", I said. "A complete stranger managed to wangle fifteen quid out of me in a few seconds. Said he was a psychotherapist and had just been mugged."
"What did he look like?" came my brother's swift response.
"He was in his 50s, well spoken, thinning hair, fairly innocuous I'd say."
"He wasn't going to Berkhamsted was he?"
"Bloody hell, how did you know?"
"I don't believe it, I got diddled by the same bugger last week coming out of the Wigmore Hall."
On hearing this, I have to say that I felt a great deal less stupid. Anyone who can pull a fast one on my elder brother has to be pretty bloody good. This guy knew exactly how to make his victims search their own souls and question their own sense of compassion and fair play.
I have since learned that this particular confidence trickster has taken in a number of well respected journalists. So if by chance a respectable, well dressed man should approach you in the street and ask politely for £15 to get to Berkhamsted, I'd urge you to administer a sharp, well aimed knee in the knackers and continue on your way.
Alex Pearl is author of Sleeping with the Blackbirds