Question: At the end, does Shirley go back to her old life or does she stay?
Answer: That's what you're meant to be left wondering. I get the feeling that she will eventually go back to her life in England but her husband will have to do some serious listening first about the changes that have to be made.
Answer: My thoughts are he stays for a while, loves it, so they fall in love again and stay together in Greece.
Question: In the scene where she is walking home in the rain after visiting her prostitute friend, in the background you can see 3 huge "tank" like structures. They are made twice as high by open girder and cable contraptions. The same things can be seen in the movie, "Spider", starring Ralph Fiennes. What are they?
Answer: Gas storage tanks.
Answer: Shirley stays. You can see that she has found herself and has fallen in love with herself and the life she created. After a life changing moment like that, she realises she can never go back again. She simply doesn't want to. At the end as she watches her husband walk toward her, you see that she observes him from a different perspective. She feels compassion, and she feels sorry for him even mentioning she hopes he stays a while to feel the sun on his face. You can sense the compassion she has for him in a more detached way and in that moment, you know without a doubt that she stays.