[quote=
a mixture of Loniceria and Hawthorn so the
hawthorn gives strength to the hedge and makes it almost imposible to
penetrate.,
I have that with a wire fence in it as field boundaries, and I have it
to over 8ft heigh.[/QUOTE]

Dave, Thanks for the mixed hedge suggestion, it also introduces a native element, I haven't seen Hawthorn lower than 6' but will investigate as it is more friendly than barbed wire, a friend suggested steel rods pushed into the ground and hidden in the foliage, tempting but better not!
MikeH