Apologies for the delay Eccles, I've literally spent 1/2 an hour trying to get back onto AB for the 1st thread to reply but it won't let me grr...
Tilly, I don't have the massive borders that I would like, but do get carried away with ideas every time I visit RHS Wisley ;-)
What I was going to say was, I have tried in vain to grow evergreen clematis (spent a load of money on a plant that just went pfft) so wouldn't recommend that.
Boston ivy is a rapid grower, but can be trained to go around other climbers. It's evergreen with a lovely red, however, mine are not-so-fast growing as they are in a very shaded area.
I would love to recommend Kiwi's to go with the other two mentioned on ric.ror's thread, although not evergreen if you get the hardy ones they have the most beautiful large leaves (fleece-up in winter if not hardy variety and get 1 male and 1 female plant for fruit (twine together))
Or again the Climbing Hydrangea:
http://www.thetimes.co.uk/tto/life/property/gardens/article3478308.ece
If you want nice plants to combine at the bottom I would say try:
Blue Scaevola (matches the potato vine in colour) or
Crocosmia (for a lovely orange contrast):
or
Tiarella 'Mint Chocolate' for a nice silvery contrast between the two:
http://www.finegardening.com/plantguide/tiarella-mint-chocolate-foam-flower.aspx