Tut,
I believe Kenny is commenting on your spelling.....since you comment on ours so often! hehe
Is the owner of the land making a complaint against your son? Do you know him? Have you spoken to him (be careful with that part, I'd maybe approach him to say sorry

If he doesn't care....a wee letter to the PF from him could kill all of this!
Agree on the comments above about best evidence (chewed L plate displayed shows that the law was respected, albeit it should have been properly maintained/checked.....if you are being fussy.....and they were!) and having someone untrained defending themself.
PS
Can chat in more depth tomorrow.