All horses must now be passported, and it is illegal to sell a horse without one.   The passport should accompany the horse whenever he/she is travelling or being moved, if stopped the police can demand to see it and it's not legal to travel without it.  All foals must be passported and microchipped before they are one year old. Microchiiping is not compulsory for older horses, just those born after June 2009, but it will probably become law sooner or later.  I don't think vaccinations are compulsory by law, but they are compulsory for affiliated competitions and many livery yards also now insist on them.  Livery and loan contracts are also recommended but are not required by law.