I was not involved with the Shetland Lamb PDO application 20 yrs ago. The most notable advice I can give you is that The Regulations do not permit the exclusive use of the breed name (and possibly an apple variety name) . So lamb from any flock of Shetland sheep can be called "Shetland Lamb" but only lamb derived from the Shetland breed that is born, raised ,and slaughtered in Shetland can use the PDO symbol.
The most recent successful Scottish protected food name application as made by http://www.dunlopdairy.co.uk/ They will have all the latest info. I am happy to answer any further questions. Good luck.
Regards, Richard