By far, the more interesting articles I’ve seen thus far about the Tonbridge Heist was the one in The Independent which posed the question, “ They pulled off Britain’s biggest raid, but the police are closing in. What will the robbers do next?”

Dumping the money was the smartest thing the robbers could have done. When police found bank notes worth up to £15m in the back of an abandoned white van on Friday, it was easy to imagine that the gang responsible for the Tonbridge heist had left the money after panicking or being disturbed. But as police made two arrests yesterday, and an emotional statement was read out on behalf of the family kidnapped in the raid, another theory emerged.

Three highly professional south London gangs are now the main suspects and, money-laundering experts believe, leaving some of the loot behind may be another example of the robbers’ meticulous attention to detail.

If the notes discovered in the van had been newly printed, they would be very hard to get rid of. “It would be very foolish to try to spend them or deposit them in a bank account in this country,” said Prem Sikka, professor of accounting at Essex University. “The serial numbers would make them easy to trace.”

Far better to abandon them and carry off only used ones that had been in circulation already and would be untraceable - and which may have been worth up to £35m on their own.

Even for a group of skilled professionals, there’s still significant logistics involved in transporting and laundering large quantities of cash, and plenty of ways the whole thing can come unraveled.

The cash presents a physical problem. The IRA raided the Northern Bank in Belfast in December 2004 and stole £26.5m, but the Irish police found £2.3m stuffed in a wheelie-bin at the home of a suspect. The Tonbridge gang will have had to work out what to do with 800,000 pieces of paper, weighing up to 900lbs.

There are ways to launder that volume of cash, despite the ferocious laws introduced recently to track and stop terrorist money, but to do so will take expertise, time and patience. Vast amounts of patience. Far more patience than bank robbers and their accomplices usually have, however professional they are. Somebody usually cracks.

As the article points out, laundering cash is an extremely high-risk activity, both in terms of operational complexity and not getting caught in the process. The £2 million reward doesn’t make things any easier–that’s a lot of money, especially since it would be legitimate. For the small fish in the plot, it’s a lot of money. The risk of claiming it, however, is that you’re almost certain to wind up dead at some point after claiming it.

A few of the ways the article suggests it might be done include…

COUNT THE CASH. If there are any new, traceable notes, chuck them. Prepare for prison. What we are about to describe is theoretically possible, but the chances of success are extremely slim

BURY IT, put it away, stick it in an inconspicuous lock-up or security vault for as long as you can bear to do so, at least until the fuss dies down. That might take a year

…

TAKE THE MONEY TO A COUNTRY where the customs officials can be bribed to certificate your cash as clean. Start a company. Experts suggest the Balkans would be a good choice

START ANOTHER COMPANY IN DUBAI, where directors do not need to be named. Use the Balkan money to buy expensive products from it (which need not exist)

TRANSFER THE INCOME from Dubai to a tax haven such as the Cayman Islands where secrecy is assured. Set up a blind trust and nobody will know it’s for you

Personally, I think that the cash is being used as collateral for some other large-scale, illicit transaction like a major drug or arms deal in much the same way that things like stolen artwork are used. My pet theory is that it’s armaments and the cash is currently sitting somewhere inside the former Soviet Union, despite having absolutely no evidence to support that theory. Maybe it’s

Eventually, the cash will begin to leak into the legitimate market, but I don’t think it will be the thieves who launder it just like I strongly doubt that it was stolen primarily to be “laundered.”