Devon,
United Kingdom 
How hard can I prune a privet in September in Devon?
14 Sep, 2014
Answers
Hi, I agree, these are ****** near impossible to kill without actually digging them out, Derek.
14 Sep, 2014
Yep, I cut mine right down to the ground with a view to getting rid of them and they grew back the next year.
14 Sep, 2014
Previous question
As hard as you like. I cut mine back in October last year from over 9ft to under 18" and it survived (unfortunately) in the Midlands.
14 Sep, 2014