Age of Consent (1969) is a story about a middle-aged Australian 
  artist (James Mason, with an Aussie accent, sort of) who has lost his 
  inspiration, so moves to a remote island to recapture his connection with 
  nature. (The film was actually lensed on Dunk Island in the Great Barrier Reef 
  area.) His nearest neighbor on the island is a crazy old alcoholic granny and 
  - here's the good part - her very young and free-spirited granddaughter 
  (Helen Mirren), who becomes the artist's model and muse. Various mischief 
  ensues. There are some sub-plots about the girl's would-be boyfriend and the 
  artist's former colleague who visits and steals some money, but the point of 
  the film is basically Helen Mirren getting naked and James Mason painting her 
  to reinvigorate his ... er ... artistic muscles. 
  While not exactly a weighty milestone in cinema history, Age 
  of Consent is a very pleasant, old-fashioned movie with the additional kicker 
  of copious nudity. Made in 1969 in Australia, 
  it exercised that era's new sense of social and cinematic freedom with plenty 
  of sensuous flesh from a young, curvaceous, pre-regal Mirren in her nude 
  debut. While the script has some serious underlying ideas and is not precisely 
  a zany comedy, it has plenty of laughs. I guess it's what reviewers used to 
  call a gay romp, back in a day when that phrase had a different meaning. 
  The nearest film in spirit is probably the legendary 
  nudefest Sirens, and there is a very direct connection between the two films. 
  Sirens is a fictional story about a genuine Australian artist named Norman 
  Lindsay, who lived apart from civilization with his family and his coterie of 
  models in a tropical paradise where everyone frolicked about guiltlessly naked 
  while Lindsay painted and sculpted them into works of art. His creations sort 
  of blend Rubens and Gauguin into celebrations of a naked female form which is 
  inevitably full-hipped, large-breasted, and liberated. Lindsay was one of 
  those guys with boundless mental energy. Not content with being merely a 
  painter and sculptor, he was also a prolific editorial cartoonist, a novelist, 
  a poet, and an author of children's books - although you more 
  conservative types might not want your children exposed to Lindsay's thought 
  process.  
  Here is 
  his Wikipedia entry if you would like a quick summary of his achievements. 
  You will notice that among those achievements is a novel called Age of Consent, 
  which brings us to the connection between this movie and Sirens. 
  Lindsay certainly knew a thing or two about the subject 
  matter of this film since it is partially autobiographical. James Mason, 
  imperfect accent notwithstanding, was in top form as Lindsay's surrogate, and 
  kept his usual oily mannerisms completely in check. Mirren, with her abundant 
  hips and breasts, had (still has actually) the perfect body for a Lindsay 
  model. At various times Mirren swims about in the buff, poses for nude 
  paintings, and just admires her own impressive knockers in the mirror. 
  Overall, Age of Consent is a pleasant way to pass the time, and was a moderate 
  hit in its era.