This must be a unique way to damage a Plus 8.
Very sorry to hear this, and Ian did well to trace the owner of the pony. But probably not unique here in the New Forest. A few years ago the bonnet of my Honda S2000 was damaged by a pony which took a dislike to its own reflection in the bonnet and attacked it with a front hoof. I was in the car but couldn't get away (in reverse) fast enough, due to the empty school bus behind me. The pony had galloped off by the time I tried to identify it and trace the owner (usually by ID'ing the way the tail is trimmed). My daughter had a pony sit on the bonnet of her Saxo. Maybe we are just an unlucky family.

The owner has been identified and the horse is insured against 3rd party damage so the claim is in process: my view is that all horses in public places should carry 3rd party liability insurance.
The Forest people are quick to point out how many animals are injured or killed by cars/vans, but not how many parked cars/vans damaged by animals. I suspect that it i more than most people realise!
((For those unfamiliar with the New Forest, there are 5000 horses, plus some cattle, sheep and pigs roaming freely over 566sq km of the forest))