It's definitely a plant.
Whoever you get, you need to make sure they're properly insured for damage, third party injury, doing a proper job. How big are these trees?
Next door's cat walked down the road with a Dunnock in its mouth yesterday. They're the birds I'm concerned about.
Does it need to be 4m high? The work in a hedge increases exponentially once you have to leave the ground to cut it (and particularly if it's wide across the top).
Pictures would help.
Sadly, a female crashed into our window and died last week. We get hardly any casualties of this sort.
One of my n's is missing.
Are the oak trees on your land, and do they have any protection (TPO or Coservation Area)?
What a splendid plant - I've never seen one.
I missed the bit on the thread title about the length and height. However my other questions still stand.