Annuals wise, Ipomea Purperea is reliable, & on a north facing wall the blooms will last longer at the height of summer.
Whilst Eccromocarpus scaber is described as a tender perrenial, mine lasted five years at my old house & was still going strong in march '08 when I moved.
Then you have the usual suspects, ie; Jasmine, Clematis etc.

thank you - I forgot to mention, it would need to be happy in a pot,!

Eccromocarpus Scaber then in a pretty big pot. Cut it back to 12 or 18 inches of growth at the end of the season & stick it in the shed or garage till mid march.

I have just looked at this, and it looks beautiful and perfect for what I want, thank you!