I hope I don't offend any law-abiding upright Mancunians but I can't help thinking that Manchester could also be known as Scam Central as it is where so many of the 'popular' scams originate.

I was reminded of this when I exchanged a few emails with a retailer in Northern Ireland who has become so thoroughly spooked over highly aggressive telesales with Mancunian accents that he now hangs up as soon as he hears them, but still suffers the anxiety that the calls arouse. He doesn't want his name used because, as he puts it: "This ordeal has made us paranoid about telling anyone outside our customer base that we even exist."

His callers have represented the old Data Protection register scam and the various bogus wall planner and drugs awareness type 'publishers' and more recently a 'crime prevention advisory service'. Part of the cheek of these callers is that they pretend to be part of an authority which is charged with public protection of some sort. This man's ordeal went beyond the pale when one caller offered to send someone round to rough him up. He went to the police and to his trading standards officers (TSOs) who have been extremely helpful. He has gone ex-directory and sent threatening debt collecting letters on to his TSOs, who have said they are investigating the companies involved.

I have speculated in the past on two things - that the operating methods of all these crooked companies is so similar that they should lead back to some common thread. And with so many of their roots going back to Manchester, that there might actually be a Mr Big behind them all.

Well, according to one of the TSOs involved in the investigation, there is a head honcho and he is currently residing at Her Majesty's Pleasure but still pulling all the strings on the outside operations. When the DTI closes in, winding these companies up in the High Court, Mr Big starts up another one based on the same tried and tested formula.

The advice, as always, is don't ever pay them anything. That will only encourage them. They are bullies and they are illegal, therefore they will never actually take you to court. Debt collectors, often part of the same firm and therefore equally illegal, need robust handling. Then they will move on to softer targets.