Here's the blurb from the 'Star Wars Aficionado - Making of SW 2004/5 & 2007 update' segment on the subject: (nothing definitive)
April (EXACT DATES UNKNOWN)
LARS HOMESTEAD - KITCHEN INTERIOR
One day was spent filming the scene of Shelagh Fraser as Beru talking to Own in their Kitchen, and an additional scene, later cut from the final theatrical cut, of Beru using a milk dispenser. Fraser's voice would be dubbed for the film's release by an unknown actress (who would then be re-dubbed herself, for unknown reasons, for the STAR WARS TV version in 1982, before having her voice returned for the 1997 SPECIAL EDITION re-release).
redubbed for the 1982 TV version? Oh, how wrong that article is. The TV version used the mono mix so i wouldn't trust that article,
She appeared in an episode of The Professionals in the 1970's, which was on TV sometime last year. I did have it on my SKY= box, but accidental deleted it. She didn't have a strong accent in it but more of a generic "film" British accent and , from what i can remember, sounded very similar to the voice used in the stereo mix. If the episode airs again i'll do some proper comparisons
EDIT: i've found an episode she was in online. Here's the clip: