Not of any help to Ginger Horse but I thought I would just say that I have kept photocopies of the passports of my horses/ponies - it just means that if there is ever a query like this that I can track down the information and pass it on - it is also useful as if a passport is ever stolen or lost it can be replaced easier and quicker. My OH even suggested taking a picture the day of purchase of the photocpy next to the original passport as extra proof with a copy of the newspaper that day to show provenance.
At little over the top I know but having been in a situation where proof was needed it was invaluable.