I expect the money laundering regulations would get you quickly enough.
We were thinking of this, back in 1963, just after the Great Train Robbery. Millions of dirty old notes, numbers not recorded, en route to the Bank of England for destruction, were lifted. They were all in sacks. And, a few days later, a few sacks were found in odd places. So there was naturally much idle chat about what you'd do if you found a sack.
The idea advocated by an older (and wiser?) colleague, to avoid it's being traced, was to hide it, and take some, placing 100 quid on a horse - a favourite. Double up each time you lost. Eventually, you'd win. Take winnings as a cheque, place apparently honest cheque from bookie in bank account. Repeat until sack empty and bank account full. Then stop gambling, before your bank account empty and bookie's full
MG