Few shoppers are aware that one in every ten cans of beer on sale is illicit, because the alcohol duty hasn't been paid.
Or that 28,000 truckloads of illicit beer trundle up and down our motorways every year.
Or that of the 450m litres of beer exported, supposedly, to the continent in a year, only 180m litres is actually needed over there.
What about the rest? Well, some of it is sent back from bonded warehouses on the other side of the Channel and then sold cut-price to off-licences and other shops, without any duty being paid.
But much of the booze never crosses to France or elsewhere in the EU. It is taken off the lorries before the crossing and sold on, without anyone troubling Revenue & Customs with a duty payment.
Then, to complete the subterfuge, the lorries board the ferries empty to make it appear that they really are pursuing a legitimate export trade, which isn’t subject to duty in the UK.
Add to that the straightforward smuggling of foreign beer and wine into the UK by hundreds of well-organised gangs and you have a massive problem.
Revenue & Customs has cranked up its efforts to collect the unpaid alcohol duty. It retrieved £433m in 2010-11. But MPs want to see more of the gang leaders put behind bars.