As police begin the hunt to recover the millions stolen in the Tonbridge heist, how might the robbers try to launder the cash?
Scene of the record-breaking robbery in Tonbridge, Kent
Millions in banknotes may sound like a thief's dream, but shifting at least £25m, and possibly as much as £50m-worth, is no easy task.
That much cash, in say £50 notes, would amount to 800,000 pieces of paper.
It would stack up to 40 storeys high and would weigh about 900lbs - nearly half-a-tonne, says money laundering expert Jeffrey Robinson.
The robbers' greed could be their downfall, he told the BBC.
"They have a real security problem in dealing with that much bulk and that many pieces of paper.
"If they'd stolen £4m they could have walked away with it. £40m is probably too much."
But what about the banknotes themselves? Will they lead detectives to the perpetrators?
Bob McCunn, the solicitor hired to track down the money and gold taken in the 1983 Brinks Mat robbery, said he understood that about £25m of what was stolen was money in transit from the Bank of England to banks and other cash retailers.
If that was the case, it was quite likely their serial numbers would be known, he said.
"They'll be instantly traceable. If somebody tries to pass one of those notes, it will be traceable back to the robbery," he said.
"So there's a huge difficulty in disposing of, in laundering as it were, that money.
"The rest of the money I understand was money heading in the other direction, it was money coming in from retailers, supermarkets and so on.
"It's very unlikely that any numbers of those notes will have been recorded. So those notes will be more easily passed."
Until the Tonbridge raid, the £26m Brinks Mat robbery, in which 6,800 gold ingots and diamonds were stolen from a warehouse at Heathrow Airport, was the largest haul stolen in Britain.
The gold was melted down and turned into poorer grade gold, before being sold and converted into cash. It was then put in various bank accounts and invested in property both in the UK and abroad.
Land and properties in London's Docklands, the Costa del Sol and Florida, as well as an oil well in Kansas, were all invested in with "dirty cash" linked to the robbery.
The Brinks Mat robbery saw £26m in gold and diamonds stolen
Although the gold has never been recovered, to date Mr McCunn has recovered about £26m for the Brinks Mat insurer.
But while UK property may once have been a safe bet for launderers, this option is now largely closed to villains.
The laws governing reporting of suspicious money flows have been tightened up under the 2002 Proceeds of Crime Act, making it far harder for the criminals to discreetly invest their loot in a piece of real estate, for example, or a work of art.
Estate agents, solicitors, accountants, bankers, casinos, car dealers and many more, now face prosecution if they knowingly - or negligently - allow crime proceeds to be laundered.
This can carry a jail term of up to five years and/or a heavy fine.
Ken Farrow, head of fraud at Lloyds TSB - and a former detective chief superintendent in charge of the City of London Police's economic crime department - believes the well-planned nature of the robbery suggested a plan on how to dispose of the cash was in place.
Even so, any large cash deposit in a bank will now immediately set alarm bells ringing.
"We've already got systems in place to look for unusual transactions," he said.
"Any unusually large-scale transactions that were out of the ordinary would be noted, and we would react - and report them in suspicious activity reports (SARs) to the National Criminal Intelligence Service."
So what other options are open to the gang?
According to Nick Kochan, author of The Washing Machine, a book on laundering, they may try to smuggle the money abroad, to a jurisdiction "less scrupulous".
Another alternative would be to deposit small amounts of cash in bank accounts in order to avoid suspicion - or "smurf" it.
"If you set up a bank account with a small amount of cash, the bank is less likely to start asking questions," said Mr Kochan.
But, according to Mr Farrow, they would have to open "thousands upon thousands" of accounts to move such an amount.
"It's unlikely that money would be passed through the banking system like that. All our branches and staff will be alerted to look out for high value deposits," he said.
Patterns of turnover
One other downside in trying to open so many accounts would be that the thieves would inevitably have to involve many more people in the crime, thereby adding to the risk they may be shopped to the authorities.
A final option would be to put the cash in dribs and drabs through a number of already established businesses.
"You'd need a very large network of businesses to launder that amount," continued Ken Farrow.
"Unless they have got lots of money to prime the network, it's going to show up if a small or even medium-sized turnover suddenly changes its pattern."