Red robin hedge

Hi all

I have a red robin hedge 5 years old dividing me and my neighbours but on my boundry so it my hedge.  On my side the plants are healthy and up to last year healthy on the other side.  Today I went to prune my neighbours side I was shocked at the condition, lots of leaves have what looks like lead curl.

I have tried to cut out the curl and prune back but had to stop when I got to the upper most part of the hedge near the fence and opposit my neighbours kitchen door.

The leaves and stem are covered in a slimy substance which looks like grease, oil or syrup.  It's strange because there is no problem on my side.  

Any suggestions on what it could be.  Could they be tipping cooking oil on the plant!  What can I do to save the plant?

thanks