Keith_Beef
Novice equestrian, accomplished equichetrian
To use Poldark as an example, I can only be honest, and say that when Demelza rode in a scene I was looking at the horse, and her clothes, but when Ross rode in a scene I was looking at the horse, and Aidan Turner. For me, I think it most of the time is simply down to that I'm a heterosexual female, I like looking at a handsome man riding around on a horse in a scene.
On the subject of Poldark, I've read that Aidan Turner had done a little riding as a kid + in The Hobbit, but nothing major, and that he sometimes needed a stunt double in the first Poldark season, but he did his own riding scenes in the following Poldark seasons.
On the page where I read the above, it also said that Eleanor Tomlinson was the best rider on the set, that she grew up around horses, and can gallop riding side-saddle.
Whereas when I look at the first of your pictures, I'm looking at the tack, the horse, the boots, the coat and waistcoat, the hat (I have a tricorn that I don't wear anything like often enough). And when I look at the second one, I'm looking at the horse, sure, but that red hair streaming out in the wind, the woman's face, and wondering what boots and other things are hidden under that long coat... You've got me googling for pictures of Eleanor Tomlinson riding horses, now.
The picture of Julia Roberts in Mongolia is nice, but she doesn't do anything for me, never has, not even when she's dancing to You Can Keep Your Hat On.
So is Aidan Turner (lovely fellow though), but he's got a bit better at it over time. Hugh Dancy can really ride, we did a few dressage/alta escuela lessons when he was filming King Arthur.
