I live in Cornwall now and have previously lived in Exmoor, Wiltshire, Cumbria and Northumberland, amongst other places! (I’m quite old :/ )
Twenty-thirty years ago, Exmoor and other parts of Somerset, Devon and Cornwall used to have a lot of well-maintained beech hedges. Sadly, the way the economics of farming have gone in the last 30 years means the majority of them are no longer maintained and have become straggly lines of beech trees, which the wind strips every October, instead of wonderful strong thick shelter which keeps many of its leaves through winter.
In Wiltshire we had a hornbeam hedge which did indeed perform like the books say; trimmed correctly in summer it would stay thick and keep its leaves through winter. But it was in a relatively sheltered spot, and I don’t know whether it would have worked as a field boundary somewhere wilder.
My initial reaction to your post was how high up are you? Isn’t much of Scotland is too far north / high / cold for beech? But if beech grows well locally then no reason to not try it. And if beech would work then maybe hornbeam would perform equally well.
I suspect hornbeam trunks might grow more slowly than beech, but that’s a hunch rather than knowledge. But if you only need a 6’ hedge, the slightly slower growth wouldn’t be an issue and might even help establish a nice thick hedge.
I’m not aware of any disease issues with hornbeam, but I’m no expert.
There’s a fab company in the far north of England, called “Trees Please”, who supply a lot of trees and shrubs to farmers, environmental schemes and the general public across Great Britain. They’re very knowledgeable, and often know what will work well where. Lots of great info on their
website, and they were happy to chat when I used them a few years ago. (Mind, we were buying a few thousand trees for the farm in Cumbria, so I guess they thought I was worth spending a bit of time with! Lol)
Let us know what you discover, what you choose, and how you get on!