Are there any regulatory height restrictions with regards to that in your local?

Fast-growing shrubs might be more to the point, Daveandsarah. Fast growing trees would be hard to control once they reached the desired height, and their roots and trunks are likely to push over the fence after a few years. You might also want to give a little closer indication of where you live in the UK--we don't need your address, but the best choices in Oxford could be quite different from those in the Scottish Highlands!

And at what height do you want to restrict the view? Many larger trees develop long trunks with foliage much higher up, so if you want the view blocked at 8 feet, eventually it won't be, as the tree gets taller.... If you could post a photograph of the area, that would be a great help in making recommendations...

I would say that my fellow gardeners have hit the nail on the head. Any tree which is fast-growing will not stop at 8 feet and will go on to be a beast and an inconvenience in your garden. The evergreen consideration will limit your choice. I would suggest that you consider an evergreen shrub, perhaps the Portuguese Laurel, Prunus lusitanica. I think that you will have to be patient as any shrub which you would want to buy at 8 feet will cost you a fortune especially if you need to plant a hundred foot run. The beauty of an evergreen shrub is that it will still give you privacy even when deciduous trees have lost their leaves.

Hi, not bothered about the height, it will be a new housing estate being built, garden is 400 ft away from house, did not think shrubs were a good idea as I would like to encourage birds?

For this situation you could combine some of the following, silver birch, budleija, Rowan and laurel, you could leave these to their own devices which will see them get very big and every so often give them a prune, the back of the fence you could plant out with common laurel, quick to get going and either you could let them form into trees or into a thick hedge you will have a lovely dense backdrop which will keep you private, in front of this lovely screen you could dot some birch these will stand out fantastic with the dense green backdrop, you can add some other smaller trees or large shrubs of your choice, over the years I have used similar combinations for my clients to screen awkward areas etc.

sounds like a situation crying out for a native mixed hedge which will attract more birds than a run of one variety of tree. Given the distance from the house you could stand to plant well away from the fence so that you can still gain access to the fence for maintenance and to avoid the problem of branches overhanging the neighbouring property. The space between the fence and hedge needn't be dead space as you could include all sorts of things to attract wildlife (small ponds, nettle beds, log piles, nesting boxes .....)

I couldn't imagine having to do the maintenance on such a big garden (4 times the length of one of my past gardens that I found overwhelming) but I could happily sit and make plans for that sort of size.

On the point about bird life, birds are perfectly happy in large shrubs too - Prunus laurocerasus gets 25 feet if left unpruned, and they'd be happy in that.

Trees are sold in various forms, but even a whip would be 5 to 6 foot high when you buy it. The problem is your requirement for fast growing - the fastest growing is probably Eucalyptus gunni, but you may not want a 95 foot monster that drops curls of bark everywhere as it ages, and which may be susceptible to death in cold winters.

Probably the best answer is to select 4 trees, spaced 25 feet apart, (the average crown size is 25 feet across, eventually) then, at least 5 feet in front of those (preferably 6-8 feet to allow for growth) and so that they fill in the gaps between, plant large shrubs, such as Prunus laurocerasus, Cotinus coggrygia Royal Purple, Abelia triflora, Pittosporum, Buddleia davidii (one of the larger ones), Cornus alba 'Elegantissima', there are loads to choose from. Some of these may not do - it depends whether your soil is acid or alkaline, damp or dry, and how cold, hot or windy or exposed the situation is, and what part of the country you're in.