Posted: 28/03/2015 at 19:07
Hi Northern Clay
Cutting the hedge back as your neighbours have done will thicken it beautifully on their side. There's a gardening saying, Growth follows the knife'.
What you should really do is trim your side back properly too.
Growing other plants against or through it will weaken the beech's growth and there will be fewer leaves and even more reduction in privacy. If a beech hedge is kept trimmed back it will retain its leaves, even in the winter, so you will have privacy then too.
Make sure that grass etc doesn't grow right up to the base of the hedge, and sprinkle the area around with some Fish, Blood and Bone (as directed on the pack) - this is a slow-acting fertiliser which will encourage good bushy growth throughout the spring and summer.
This site http://www.ashridgetrees.co.uk/gardening-advice/how-to-plant-hedge/beech-hedging-pruning will give you more information.