1. Cable knows his Onions. He has been as constant as the north star on this, where the Tories' position has been complex and changing. Who in Britain can explain what the Tory position is? That's the problem.
2. Cable works hard at it. He's on the phone now, talking journalists through the wider points and finest detail in language so engaging that the rest of our train carriage (incl. Chris Smith) seems hooked. He speaks to merchant bankers, industry experts and is impeccably well informed. He is a one-stop shop for journalists, and has made himself the first call for any broadcaster seeking to demystify this baffling issue.
3. Cable is older. It's a benefit in finance, where people want a Chancellor that looks and sounds like a trustworthy bank manager: Osborne's youth is, in this area, a disadvantage.
4. Cable has looked beyond party political point-scoring, and focusing on giving a firmer and clearer explanation of events than anyone else. That is how you gain credibility. The Tory strategy can be summed up in five words: "Gordon Brown, ha ha ha". Cable has risen above this, hence the halo.
5. Cable is former chief economist at Shell. Packed with real world experience he is that rare beast: a politician who is properly qualified for the brief he holds. He talks as an expert, whereas Osborne talks as a politcian. The public far prefer the former.
This is not to trash Osborne, whom I rate highly and who visibly outclasses Darling. But the Tories should be exploiting all this far more. I bet even Osborne wishes Cable was on his team (and, perhaps, in his job). Maybe I'll sidle up to him after we pass York and persuade him to defect....
P.S. Political Betting critiques the Populus poll here.