Privet problem

Has anyone got an idea what may be causing this? There's a privet hedge along a fence line and until 2 years ago was doing well. I'm told that there was one section that did the same thing and just died off so was cut down now the next one is getting the same symptoms. It's been regularly watered through the summer. Everything else in that border is ok. I've taken a photo of the leaves they are going reddish with dark patches then they fall off. I've tried to look up privet problems but can't find much apart from honey fungus, there's no mushrooms at the base, we haven't peeled back the bark yet. I've found some interesting information but no photos to go with it so we can compare symptoms. Also various aphid or insect damage but no photos on line to compare.
It's not in my garden I'm asking on behalf of a friend so I can do more checks next time I visit if anyone has any suggestions!

 

Apologies but I am not able to put the photo on at the moment for some reason

 

Hi @Millie16 - honey fungus is the most common reason for privet dying off.
The red/black leaf drop isn't totally unusual, and can happen quite often, but would rarely be the cause of large areas dying.
When you say it's been well watered - that can certainly be a problem because watering something in the shadow of a fence is often never enough, despite thinking it is. The age of the hedge is a factor - ie how long has it been there, and how well was it doing before the problem. The height of it and what else is around it [competition] all affects the moisture levels. Privet can take any amout of water, but it won't like being dry long term [the red/black foliage can be a symptom of that] so the location of the site is another factor. In dry areas it's easy for people to think plants are getting enough moisture- until they fail.
Photos will certainly be most helpful though.