Hi Ian how 'small' is your small area? Which way does it face and what is you soil like? Finally what is your drainage problem?

Merry Xmas ..And remember what you plant for privacy will affect your light levels inside your house. A photo would help

If the problem is free drainage - how about some of the giant lavenders? They are free draining, shallow rooted and will grow to at the least 1.5m including the flower spikes in the summer. You also have the benefit of an evergreen hedge. It needs pruning twice a year only (not the first year) after flowering to take off the flower spikes and again very lightly in march just to keep it compact. Varieties of buxus are also reasonably shallow rooted. Variegated variety is not so hard frost hardy. Rosemary is another lovely scented option that can be hedged, if it doesn't get too frozen where you are.

Wow what great reply's. The garden size is about is 5ft from window to small fence and is east facing, Lavenders I will look into, A photo I dont think so lol.

Quite small..Rather than a whole block of hedge, I would try to distract the eye of passers by to the plants rather than the windows. Something striking in one of the top corners and work the eye from there.

I don't think a hedge is going to work in such a small space... think on Pimpernel's suggestion.