A criminal gang was recently jailed for one of the biggest ever alcohol smuggling rackets in the UK. It's become big business for organised crime according to HMRC, with tax losses in unpaid duty as high as £1.2 billion per year. MP's are demanding tougher action. But these are highly complex frauds, which take years to investigate. Allan Urry examines the scale of the challenge facing the authorities, and reveals the extent to which criminals have penetrated the legitimate market in beer, wine and spirits