Microchipping is an excellent way of identifying tortoises. All live Annexe A tortoises need to be microchipped to be able to be registered for a CITES specimen specific certificate which allows them to be sold. Any such tortoise over 10cm must be chipped to be legally sold OR DISPLAYED. ALWAYS CONSULT THE DEFRA WEBSITE (BELOW) FOR UPDATES ON THIS.
The species currently under CITES appendix A are (but check with DEFRA yourself, this may go out of date):
Galapagos giant tortoise Geochelone nigra or Geochelone elephantopus
Radiated tortoise Geochelone radiata
Angonoka Geochelone yniphora
Bolson tortoise Gopherus flavomarginatus
Berger's cape tortoise Homopus bergeri
Pancake tortoise Malacochersus tornieri
Geometric tortoise Psammobates geometricus
Madagascar flat-shelled tortoise Pyxis planicauda
Madagascar spider tortoise Pyxis arachnoides
Spur-thighed tortoise Testudo graeca
Hermann's tortoise Testudo hermanni
Egyptian tortoise Testudo kleinmanni
Marginated tortoise Testudo marginata
Negev tortoise Testudo wernei
You do not need CITES paperwork to possess one of these but if you pass it to a sanctuary/zoo which is open to the public they will not be able to display it or put in perhaps with others on display unless you obtain this paperwork.