Bird of prey

I have heard that birds of prey have been spotted circling certain parts of Farnham park but I've never seen one. Today I saw two! They spent ages going up and down a spiral of air, clearly looking for prey. They were also a long way up so I have no idea what they were. But they looked magnificent. I stood and watched them for ages.

Any suggestions as to what this is, would be gratefully accepted.

Looking large may help.

EDIT: Thank you commenters! 'Tis a buzzard.