What bird makes this call?

Hi there

I live in farmland area in hampshire, with a medium sized pond nearby too.
I have no idea what bird makes this call, I hear it at night mostly, and also sporadically in the daytime.
Having looked through and listened to all the sound clips on the RSPB bird pages, I cannot identify it.
My friend though it was a Tawny Owl, but it doesnt match the sound of a Tawny in my opinon.
Grateful for any help in identifying this one! 

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Cheers 
Jacki