The Owl Service
But in this book, it means 'dinner service' ie plates.
I picked this copy up for $4 somewhere, just to own it, but I haven't re-read it for years. It's fantastic, a creepy, intense tale of Welsh myth and adolescent yearning. The three-way pattern of doomed love keeps repeating through the generations, which is an idea I might have unconsciously picked up for Crow Country, come to think of it.
The magic is released when Alison traces the pattern on a set of plates and makes paper owls out of it, which was something I always had trouble visualising, but thanks to the magic of the internet, I looked up Alan Garner's website and found a picture of the original owl plate, a gift to Garner from a friend.