"If you're right that it raises no revenue, even in the short term then clearly it would be painless and advantageous to get rid of it at an early stage."
But George Osborne's policy package today contains this little nugget, taken from the press notes:
"The new 50p tax rate and associated changes to the taxation of higher earners should be kept in place for at least as long as the public sector pay freeze, in order to ensure that the richest in our society pay their fair share of the burden of tackling Labour's debt crisis."
You can see - although perhaps not sympathise - with the thinking behind this. It's part of the "We're all in it together" theme that Osborne was pushing today. But it does mean that there are more conditions for ditching the 50p tax rate than Cameron seemed to be letting on last week.