Good shot on the horse but the guard is out of focus which I find distracting. A deeper focus depth and going a fraction wider to show the top of his helmet would have made an excellent image.
As it is, I would crop square to remove the guard's face and concentrate solely on the horse's head. Having part of his arm and hand visible won't matter.
Kaye, featuring the horse is a nice change from the run of the mill shot of this subject but I think there are two obstacles - he is wearing eye capturing red and the current lack of focus isn't enough to make it look deliberate. However, all is not lost if you have access to a layers facility. Just duplicate the image, blur the top layer, add a layer mask and then use the Gradient tool from about halfway down the horses neck to the Guardsman's shoulder to gradually bring in the blur from behind the horses head to the LHS of the frame. You could also slightly desaturate everything in the BG in the same way to neutralise the pull of the red but that is a matter of choice. In case it's of interest, it should look something like this:
+10 to Geoff's comments.
That works for me.
Even better Kaye. Like that a lot.
Sorry, Kaye, the totally out of focus rider really spoils the image. You used f5.6 at ISO 100. Your camera is well able to shoot at ISO 400 (plus) so next time, try something like f11 and get it all in focus.
I really think that the success or otherwise of the image depends upon the intent behind the image. While you might see the rider as important to be in focus, a horse lover (for example) might not want the rider to be sharp as their focus is on the horse, in which case the rider is simply providing context. The thing about most images is, I believe, much in the eye of the beholder, so I would personally precede such a criticism with something like " for me" or 'IMHO'.
Thanks all for further comments. Tony, the oof was deliberate just not executed too well. But as John says one of the joys of this hobby is the experimenting it allows and the joy of this forum the diversity of friendly opinion and advice.
Kaye, I like the final version of your photo and think it works well.
Add me to the list that prefers the final version, including the crop, well done Kaye