Star Wars Insider 32 has an interview with Shelagh Fraser: 'Strange Beru': (again nothing concrete, but talks about her voice)

pg. 13:

You'd never know from talking to Shelagh Fraser that she played the reserved, nurturing Beru Lars, Luke Skywalker's aunt in the original Star Wars. First, there's the thick British accent, which the Irish-born Fraser (whose first name is pronounced Sheila) altered for the role. But more striking is the talented and talkative acress' gift of gab, which stands in marked contrast to Beru's quiet farmwife simplicity.