So it turns out that buying a house that is not for sale isn't straightforward.
I wrote a letter to the owner. In the letter I explained that my parents live across the road, that I grew up in the street, and would be thrilled to be given the opportunity to buy into an area that I know and love. I explained that we loved the charm of the home, and would restore and retain the original features.
The letter didn't get a response.
After an agonising month of waiting for a response, we found the owner's phone number. I mentally prepared myself to make the call. As soon as I introduced myself, she cut me off and said she had received my letter, and was waiting for her niece to return from overseas to negotiate with us. Success!