A row of Italian Cypress trees-tall, evergreen & they don't take up much real estate.

Thank you

Or those upright yew. Better for wildlife?

Although not evergreen, I would suggest a hawthorn, Crataegus monogyna, wonderful spring flowers, good for wild life and dense, thorny habit so it will obscure without creating too much shade. Paul's Scarlet would be another option.

You could try clumping bamboo. I have some, and it has grown less than a meter across at the base while being 5 meters tall. But that is the clumping type.

Thank you for comments yew iand Hawthorn are a bit slow never really took to bamboo hard to get rid of probably but great screening potential can it be guaranteed not to spread?. But thanks all.

The bamboo I have is about 1 meter across at the base and is over 10 years old. I grew it from seed, and have 2 clumps that are both very well behaved. They are situated 2 meters apart and screen an area 5 meters.

OK thanks I will look into that

Your photo does not show the boundary between you very well. If it is a fence and you own it you could add a trellis to the top and then grow something on it. The other alternative is to grow a tree similar to the one shown in your photo. Do you need the same level of privacy in the winter? I have a phormium (new Zealand flax) to obscure the view of my garden from my neighbours extension ground floor windows. People do not tend to spend the majority of their time in the bedroom during the day. I use bamboo in a large pot two feet diameter x two foot high to screen our patio area in the front garden from people on the drive. Privet grown as a flowering shrub, not as a hedge, will also give a fair amount of privacy. If you allow it to grow naturally it ill quickly reach ten foot high. The flowers will fill the garden with their scent.

If you look at the photo the boundary is the fence which is mine I believe and the neighbours have grown a hedge behind it which they keep short it's even lower in the front. The windows of next door go very high the current height of the hedge you see is not far off 6ft even if you secured a trellis it would have to be another 4ft higher than the current hedge height which is indeed possible to block the neibours 2 kitchen windows. Yes it's possible but growing a evergreen 10 ft high to completely block the windows would take a long time I think.

I looked at the photo again and yes it is difficult to see the fence which is painted the same colour as the hedge and is 4ft high. You have some good suggestions like large bamboos in containers ect flax would be too low. The alemancher tree is pretty but will take a long time to grow I've only got 20years to live max. The trellis is also good idea also but would need to be 6ftx6ft panels hoisted up and lots of screws