Did you see bird?

I wonder whether any of your readers can help with the identification of a bird I saw in The Byes on January 2.

It had the ‘feel’ of a seabird, although it was perched three-quarters the way up a very tall tree. About the size of a buzzard, dark brown/black apart from an off-white chest, head proportion relative to the body similar to that of a shag, with a longish, straight, pointed, bright yellow beak and a short, but obvious, neck.

I had no opportunity to see it in flight or to observe its feet. I can find nothing to match it in my bird identification books and am wondering whether it was blown in on the recent gales.

Did anyone else see it, and does anyone know what it is?

The peace of our Lord be with you.

(Rev) David JC Wheeler