SilverWook said:
Prowse has claimed for years he was unfairly blamed for a script leak during production on Jedi and things got very unpleasant on the set after that.
As far as I understand it, the Daily Mail leaked Vader's death before the movie was released.
Prowse has since claimed a reporter had somehow got wind of Shaw's role as Anakin Skywalker and duped him into showing him the call sheet with Sebastian Shaw's scene on it as confirmation, under the pretense of be interested in interviewing Prowse about his weightlifting career.
Not sure how much truth there is in any of that, or whether that is genuinely the cause of the ongoing rift between Prowse and Lucas either way.