As Dick Puddlecote points out, the media can't have it both ways. If a smoking ban can reduce the number of people going to jail, it can also reduce the number going to the pub.
Personally, I give the story little credence. A smoking ban in prisons will only increase the price of snout. Illegal drugs are, after all, widely (if expensively) available inside. If there were truth in the story, however, it should (if any actual thought underlay their positions) present a dilemma for the left. If fear of tobacco deprivation were enough to deter criminals, why stop there? How about banning TV sets? Playstations? Or, for the white-collar criminals, The Guardian? It has to be worth thinking about.
Guardian readers may also like to note that the story suggests crime is a matter of choice. However sad their family or social circumstances; however severe their peer-pressure; however vulnerable the potential criminals may have been, it seems they could choose not to commit crime.
What a heartening thought for the New Year.