David Willetts, Shadow Secretary of State for Innovation, Universities and Skills, has been talking to the Times Higher, and revealed that the Conservatives would delay the REF 'to establish whether a sound and widely accepted measure of impact exists.' He continued, '[we] do not believe that the current proposals pass those two tests. Unless the review is able to establish a measure that does, we would not include impact in the REF.'
Not sure if it will win many votes among the wider electortate, but it looks like they're winning over the academic sector with this manifesto pledge. More details on the Times Higher site.