Thanks for all your replies.
Think I'll cover the top of pergola with green canvas as suggested for this summer. I'm afraid it's the only way to cover the top. Things like runners are great if the windows over looking aren't directly above you, but when the buildings are three storeys high and less than twenty feet away it means more drastic action is needed!
Canvas will probably look ok once I have some hanging baskets and surrounding plants to take the hard edges off.
It's a nice idea to leave a good garden legacy for the next owners... sadly every time I have moved, the next owners have ripped out my carefully tended gardens and started from scratch - something I will never understand.
We all want to make a garden our own, but It's lovely to start with a few well established favourites. You can't buy a mature apple tree with a good crop from a garden centre now can you?!