In one area this year, they seem to be trying to discourage this - they are allowing people to see the answer sheet but no question sheet - not a lot of help for VR / NVR (unless there are chunks not marked).
In Gloucestershire this is certainly the case. I would assume that it's because one of the papers is reused after a few years, so parents with photographic memory (or a hidden camera) could copy the paper.
Here, the answer sheets can be produced at an appeal should the parents or panel ask to see them, as the school side will (hopefully) have brought them along (if not, then we'd probably adjourn the appeal until they were produced). The schools also seem to have a policy of re-marking by hand all papers for an appeal.
So far I've never known the outcome of an appeal rest on the answer papers, apart from the one time the appeal was cancelled because the school found one answer marked as wrong that should have been right, thus taking the child over the pass mark, and immediately offering them a place.