Posted: 05/08/2014 at 17:59
Welcome Mick. I'm afraid unless as bekkie has said you spend more than a few quid, your wish won't come true. Going down the clematis armandii route will give you an evergreen screen, although it will get a lot bigger than 8 feet. Even a clematis montana will grow a lot taller. However having said that in winter with a bit of training it can provide a dense screen of although bare branches, it is difficult to see through, ask my neighbour at the back of me. The trouble you may have is the weight of any climber as you don't say how your trellis is held up.
A rose will lose it's leaves few will keep their leaves to any great extent.
Have you thought of bamboo, or a tall shrub, although again you have the issue of speed of growth.
There must be someone here can make another suggestion, so be patient.