Planting a tree for privacy?

[doblet]

Our house is overlooked by just one window from the house behind us. The neighbours always seem to be staring at us from it. Just how much time do they spend in their bedroom?!
We would really like to plant something that will eventually give us a bit more privacy, or at least break up their view of us.
Any suggestions?

i'd have something evergreen so you get privacy in winter. also think about how tall and thin it needs to be, ie how close to the fence and is your neighbour going to chop half it down if it overhangs their garden.

I know the feeling - we have neighbours behind who chopped down a conifer hedge and they now stare in directly into our garden from their windows. I planted a row of small trees and cherry laurels to create a screen (eventually). I've got a flowering cherry,a Sorbus aria lutenscens and a Robinia and they are all lovely trees!

Sorbus is here www.crocus.co.uk/plants/_/trees/other-trees/deciduous/bigger-trees/sorbus-aria-lutescens/classid.4716/

Robinia is here www.crocus.co.uk/plants/_/trees/other-trees/deciduous/bigger-trees/robinia-pseudoacacia-frisia/itemno.TR00007311/

Thanks for the suggestions, I'm off to google