Audio clip of unknown bird

It's the one repeating every few second in the background.

Try Golden Oriole :)

Already thought of that when I first heard it, but although it is similar, not sure whether it is the one.

Had a listen to your track and it certainly sounds more like it than the others I've heard, the secret nature of the bird would certainly fit, shame I had the dog with me when I recorded this, as there was no chance of stalking it.

I'm thinking back to last may when I was in the same wood and what I thought was a couple of Jays screaching, was probably a couple of Golden Orioles, will have to take the hide into the woods next year and spend a whole morning there.