The head of the CPS economic thinktank, Ryan Bourne, has tweeted that Labour's policy would not work:
Ed's numbers don't add up. Either mansion tax would have to be huge, or 10p rate tiny.
Ed Miliband has turned political cross-dressing into an art form and has now laid claim to the party's reputation for cutting taxes.
Labour have unveiled two big economic ideas today, neither of them is particularly new and neither of them is particularly effective.
Ed Miliband and his shadow chancellor Ed Balls couldn't have been clearer. Scrapping the 10p rate of tax was a very, very bad mistake.