Posted: 18/09/2017 at 20:48
If your friend is keen on the idea of pleached trees, you could suggest Hornbeam or Beech. Not strictly evergreen of course, but they retain their foliage over winter, so you would always have a screen there. However, pleached trees are not a low maintenance option.
A row of columnar yews would do the job. Easier than conifers, although there are plenty of those that would fit the bill, but you have to be vigilant with correct pruning.
Nothing is going to quickly fill the space either, but anything evergreen will need pruning and shaping at some point, and regularly, to keep a more contemporary look, so that will need taking into account.
A classic solution is white stemmed birches, which, although deciduous, are very striking and eyecatching because of the trunks. The idea is to use the wall as a backdrop, rather than seeing it as something you need to hide or cover up. There would also be the option to put something underneath to help detract from the wall. Something with a structural shape like the rounded Hebes would be ideal, and would give a good contrast. It would be most effective if taken along the full length of the boundary too. and would be much lower maintenance and more interesting than hedging or bamboo.