“Hey, no problem,” says the young woman with the dubious American accent. “Take care, yeah?” But she says this to all the boys.

Over the next 20 minutes, I hear the same line 50 times. “Hey, no problem. Take care, yeah?” It rhymes. It has rhythm. But hey, it’s driving me crazy.

The woman is one of a small troupe of importunists whose impossible mission this Friday afternoon is to approach commuters as they run for their trains and sell them a “platinum” credit card.

Well, not sell the card exactly, but at least persuade the unwary to “step over here for just two minutes” and fill in an application form. “Have you applied for your platinum card yet, sir? How long before your train? Listen, it just takes a minute, yeah?” They were here last week - a different team then, but with the same cheery, street-credible tactics. If you ask me, they are graduates, poised to fly high in the world of financial services. “Oh sure,” they will tell their PA one day, as they sink into their padded leather chair. “I’ve done my share of selling. Hey! I once sold crdit cards at a train station!” Well, not sold exactly. “Just step over here and I’ll explain.”

It’s one of the lads in action now, a Jamie Oliver lookalike, with tousled hair and a long tweedy overcoat like ageing rock stars used to wear. The punter has made a fatal error. Instead of fleeing, he blathers something about train times, and already a kindly Jamie, all thoughts of credit cards far from his mind, is generously helping him find his destination on the indicator board.

“Bromley? There it is, look. Platform eight. But, hey! It’s not due until 5.15. We can be through here in just two minutes, yeah?” They’re good, these kids. What’s their hit rate? “Thirty a day,” says a girl with starched black flick-ups. Thirty each? “Thirty each.”

But every week, I tell her, an envelope comes through my door containing an application form for this same credit card. “Sure,” she says. “The mailshot isn’t working. Which is why we’re here.” Such sincerity is disarming, but I check myself in time. Listen, I say. There’s my train. “Hey, no problem,” she calls after me.“You take care, yeah?” newnham@danecroft.demon.co.uk