We have trellis along the top of ours - not the flimsy stretchy wood but long panels. We are quite friendly with our neighbours so its not an issue but we both grow clematis and honeysuckle up the fence and it gives quite a bit of privacy.

Looking across the back yards here - we have ones with trellis, Thuja, a mix deciduous trees and just a fence - so that is what some people do. I have Silver Birch then a Thuja in a row of 6 each. the idea is none gets too big and will be pruned when the screen is at the right size. I only have one house that over looks mine but as my garden is higher, it feels like me peering down into their garden!

many thanks for this idea however we are over the limit for ht if we put a trellis up our neighbour (from hell) would be the first to report to the council we need something up to a height of around 8ft within our garden not on the fence

You could build a raised bed with pallets and stain them and that will give instant height. You could then add tall, evergreen growing plants such as Bamboo, Aucuba japonica etc.

I think you need to think outside the box? There are ways around this.
If you come away from the border by just a few feet towards your house you could build a double trellis or Pergola and grow either roses over it and dont prune the top growth, or something like a hop. Your neighbour could not complain to anyone nor reach to cut anything off it his side.
A tree planted in the right spot will also give some screening but take longer and the other idea that you could try in summer is garden sails?

Our neighbours, whose house is at a higher level than ours, (we live on a hill), built an unsightly extension which overlooked our patio area, so I planted Phyllostachys aurea (a clump forming bamboo) on my side of the boundary. I bought 8' tall plants which over 5 years have grown to 15', although they could of course be pruned if required, and this has screened their extension. Phyllostachys is evergreen and frost hardy.

Thank you all - I certainly have some good ideas now I particularly liked the raised bed idea. The line of vision for my neighbour is when they stand on their back door step and it did cross my mind to put a tall shed a few feet away from the fence. The raised bed with bamboo could go either side as my neighbour has attached their washing -line to my fence and washes every day - so need to block that view). Does anyone know a company reached online that sells tall (7' high) storage sheds?

I think that most sheds are 7 ft or more high, but if the fence belongs to you, you can tell your neighbour to remove the washing line from it, I presume it is some sort of hook screwed into your fence, which could allow water into the wood and rot it, and also the weight of any washing could damage it, washing lines should be attatched to a steel or concrete post with lugs on it, not a fence, just tell them to remove it, Derek.