Montagu's Harrier

Family seaside visit, lots of digging in the sand and me staring rather hopefully out to sea. We'd decided to leave but were awaiting the completion of a further sand structure when the hopeful became hoped for. What's this? Dark, large falcon-like but lazy flier, low over the sea about a klick and a bit away. I watched the raptor slowly heading west, occasionally gliding (that's the bird not me), trying to figure it out (that's me). Peregrine was in my mind, as that's what you'd expect, but it was far too lackadaisical and indirect and the jizz was wrong for any falcon although the wings were pointed and narrow and the tail a comparable length. Then it soared up and for the first time I saw it head on, classic harrier shape. The penny dropped, it's a Monty. I watched the bird soar way up and gave Louise the bins for a look (no scope of course). It soared around for a while and then dropped down again, further out now and to the west, it kept going. Whilst up high it was with a couple of Herring Gulls briefly, it didn't like them, and was smaller and slighter. I was surprised how dark this bird looked but the distance, the sunshine and the fact that they are quite dark (juveniles especially apparently) would explain that I guess, I couldn't see any plumage detail and certainly I was not able to count the primaries. it would have been nice to have had the bird closer, or to have had the scope but so it goes.