Well, I decided on none of the three options! For the time being it's a do it myself job. Using my elementary engineering skills I decided to mount the bell on a simple wooden frame and to place it in my study window until I decide on a more permanent solution if ever! Total cost of materials is £20. Could have been a lot less if I'd used old timber in stock. But sometimes a chap just likes to splash out.
Here is the frame in my improvised workshop and in it's proposed location. A mid grey coat of paint will follow. Just the bell pull to decide and then I'll have a ring in and leave it to rest for a while in it's new home.