Squeaky city bird?!

Hello! I'm Ryan and I live in central Edinburgh, Scotland. I have noticed a new bird call in the graveyard across the road from our flat, and am very curious to see if anyone knows what species this is?! It has just started a couple weeks ago and makes repetitive squeak type calls in the same note. I've tried to attach a recording - hope it works! You can hear it periodically between traffic passing. Thanks in advance for any help!

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Edit: I have just had the delight of two of them flying by my window! They are brown in colour with light brown/grey on their chest. They're larger than woodpigeons and I suspect they are birds of prey.