I spent a day with Carl Hester a couple of years ago when Valegro was 7 and he was saying he was gelded as a 3 year old (I think) before he went to the sales because his then-owners didn't think he had stallion potential. Then they took him to the sales, but felt he was too badly put together to go through the ring and stuck him back on the lorry to go home, so Carl bought him straight off their lorry without him being auctioned.
I think Carl said it was because he was not very big and very high behind.. which i guess he's grown out of now as he looks pretty lovely to me ;0) !