Mystery bird song!

Hi all!

I am in dire need of some expert assistance, I have moved to a fabulously remote cottage, and the birds are out in force. Every day I am listening to a bird I have never heard before, and I have no idea how to start to identify it! Its call resembles to sound of a lorry reversing! The low pitched squawking kind, not the high pitched beep. Its not a Barn Owl, or any kind of Owl I don't think, and I hear it most of the day! Any ideas?!

Claire.