Sacha wrote:
I would strongly recommend Hardenbergia violacea. Ours grows in an unheated
greenhouse which is kept just above freezing. It rewards us by flowering
wonderfully and if it's in a really sheltered spot, it can be grown
outdoors.

Sacha, what a beautiful flower!
http://www.abc.net.au/gardening/stories/s1460240.htm

This looks like just the plant to me, though I note what they say about
it tending to bush up at the top. Do you find that? If so, can you
force it to still sprout from lower down?

South Devon vs. 265 metres above sea-level in Shropshire. Well, it's
worth a try.

Eddy.