Wall is about 7' or just over?

The Highways Act gives the highway authority (which may be the council)
powers over barbed etc wire on land adjoining a highway. I think the
practice on that is to accept it if it is over 2.4m. Whether they
would take action if it is a bit lower is another matter: I think it
depends on whether it is likely to cause injury to users of the highway.
And IIRC the onus wd be on them to serve a notice requiring its removal.
It used to count in your favour if you put up signs warning people. But
I don't know how many languages you would have to use these days. (Are
you in Wales?)

Perhaps a word with your local crime reduction officer?
--
Robin