Prowse has been talking to the BBC Bristol website ahead of the film's 30th anniversary on May 25.
He says that accusations that Harrison Ford gave him an unflattering nickname are simply untrue.
"I think at one stage they wrote that he used to call me Darth Farmer because of the accent.
"He never ever referred to me as that, I never heard him speak that way.
"I used to get on quite well with him and in fact him and Billy Dee Williams [Lando Calrissian] at one stage bought a set of weights and I used to instruct them on how to train properly at the studios."
Prowse was also full of praise for co-star Alec Guinness, who he says gave the film "some status".
"He hated everything the came afterwards, for forever and a day he was going to be remembered as Obi-Wan Kenobi.
"Here he was with this fantastic body of work he had done over the years - everything from The Lavender Hill Mob, Ladykillers and The Bridge on the River Kwai.
"His legacy in life, once he died, was Obi-Won Kenobi and it was that he didn't like."
David Prowse was talking to BBC Points West's Chris Goodman.
We'll have more from Darth Vader next week - make sure you come back!