On 19 Sep, 09:16, harry wrote:

You need a double row @ 450mm centres. Hawthorn, holly, hazel,
elderbery etc. *It needs leaving 'til its about five or six feet high
& then "laying" by bending the stems over horizontal. They might need
a nick to make tem stay down. *This gives a dense hedge that is more
security proof than barbed wire.
You don't want dogwood, not native & runs amok with suckers.

Yes, yes and yes.

Hornbeam can be VERY slow compared to the others. I'd establish hazel
and hawthorn, and plant the Hornbeam & Holly as 'standards', rather
than including them in the laying. Then add dog rose 10 years later
to work it's way in and out. Blackthorn will spread and sucker all
over the place, but I do like it a lot, the blossom is fantastic, as
is the hawthorn. Your choice.