Victoria-

thanks for all your help and advice. I have one more question about
the 'Buxus sempervirens' (they do seem to be what I was thinking of):
the crocus site states that they need partial shade. Wind problems
aside (I can secure the pot if I think necessary), I am planning to
put these on a London south-facing balcony. Some would say that that
is partial shade enough, but do you think they would survive
south-facing?

Finally, any suggestions on the traling plant? I was even thinking ivy
might be quite good... it will be surrounded on one side by flowers
and the other by whatever shrub I buy... can you buy mature fronds of
ivy (as opposed to having to grow from scratch... remember, my aim is
to get something looking nice asap).

Climber is trickier because of the wind problem. (climbers long stems
are likely to get snapped or battered about...
Ivy is pretty tough, but anything you buy as a mature plant is going to
have more problems than something bought young that develops in that
environment.

Well, I was planning to wrap them around the metal brackets (which are
quite ornate), so hopefully that would protect them somewhat. Also,
they will be sited right between (hopefully) a buxus sempervirens and
a large stone flower trough, so wind should be somewhat subdued there.

Ivy would be fine for the climber. Can you suggest any ivy variants
that look nice (maybe variegated leaves or interesting colour...) ?
Also, can you buy mature ivy?

I'm not sure what to suggest - maybe someone else can come up with
something?

Anyone else? Please share your advice if you have an opinion

Thanks

Victoria