We bought our 12yr daughter a horse in June. She is a complete novice so we looked long and hard to get a good safe and sensible ride for her to learn on. We were delighted with him, he didnt put a foot wrong, absolutley gorgeous. He was in a field with a mare and another gelding. Then about 3 weeks ago two more geldings were added to the feild one an unbroken 4 year old and an 18 year old who is incontinent and quite simply too nutty to be ridden. Since then our horse has changed, he has bucked, gone into canter and spun round on the spot on a hack. He is still very affectionate but these things he is doing when she is on him are really unnerving her. I do not want her to get to a stage where she no longer wants to ride him. The yard owner is saying "oh he's just trying it on you have got to show him who's boss" but I don't think that's what it is. Any ideas??