[Liparis]

I think the main problem you have, Yorky, is the material. It's not been properly produced as hedging in the nursery. To produce hedging plants a bit of anual work is required, more so with beech than, say, Hawthorn. Beech is a tree and that's how it wants to grow, so, the nurseryman cannot sow the seed and allow it to grow to a saleable height. He has to transplant it after 12 months and remove the main tap root. This encourages the fibrous feeder roots. He should be transplanting it a second time about 12 months later again, and once more removing any tap root. The tap roots are what holds a tree in place against storms etc. The third year they should be undercut. Go down the row with a very sharp spade, or a machine if your a big nursery, and slice at about 45 degree angle, cutting through the roots. All this produces good feeder roots, but also encourages side shoots. Nurserymen should in fact sell by how they are grown. For example he might sell Beech hedging 2+1 or 2+2 or 3+2 that's translated as 2 yrs old and 1 under-cut etc. up to 3 years old and two under-cuts, that way you have a fair idea if you need to do any further work when you plant them to encourage side growths. 3+2 of course being a more expensive tree, but making a far better hedge. Your beech looks to me like it has been sown, transplanted and left to it's own devices.
The work you now need to do is completely diferent from the norm. You could try removing the growing point in the summer and try and get side shoots that way. But I really wouldn't do it when dormant.
Bill.