John wrote:
Just a thought as I have just had a new fence.....

Concrete posts sometimes seem to fail due to the steel reinforcing
rods corroding. Is there any point in trying to reduce moisture
getting into the concrete by using some sort of paint or sealant? Or
isn't this corrosion much of an issue on new posts?

I would say yes, give them a coat of something, preferably in summer...the
moisture can only get to the steel through the concrete, so painting them
will effectively slow this down considerably