At 40 minutes in, the camera perspective during the auto ferry disembarkation shows a sign that says :Welcome to Bala".
There is no such place listed among all the Scots islands listed at Wikipedia.
No location is provided in the credits.
The island's real name is Barra. They changed it to Bala.
watch this picture:
http://juraphotos.photofxr.co.uk/gallery/pics/0367.jpg
Morlock7
The Isle of Bala is in actual fact the town of Dartmouth in Devon, where that exact ferry is still being used today http://www.panoramio.com/photo/22252813.
It was filmed predominantly at this location, along with Dartmoor National Park under an hour away.
I remember the stories given to me by my Grandmother like it was yesterday. It was my Grandmothers Fruit and Vegetable business that supplied fresh food to the cast and crew for the filming they did in Dartmouth. My grandmother formed a strong friendship with Diana Dors on this film that lasted right up until her sad death in 1984 to which my grandmother attended Diana's funeral.
The screenplay is what drags this film down. I believe it was produced by Christopher Lee's own production company, fresh and Hot Faced off the back of The Wicker Man. Lee wanted to move away from Hammer's brand of monster horror into more psychological horror. Sadly, this was to be Lee's only film as producer.
Dartmouth hasn't changed at all. I would go as far to say that any production shot on location anywhere in the South West of England, and including for the next one hundred years, the landscape would hardly have changed upon revisiting the scene.
All the best to you.
"I was a daisy fresh girl and look what you've done to me." -Dolores Haze