Saw a Marsh harrier in the dales about 6 weeks ago, is this a rarity?
If in an upland habitat then it is a rarity, although a couple of years ago a pair nested in moorland in North Yorkshire. Usual habitat is lowland reedbeds.
It was hunting quite high up the fell over a boggy area, got some footage on video
Can you take some screenshots and post them here?
That's a Short Eared Owl. Much more typical denizen of the upland moors.
Check out this vid for flight similarities: www.youtube.com/watch