does anyone know what the criteria would normally be for judges lists re breed specialists and non-breed specialists. ie, what would someone have to have done, owned, bred etc to be a specialist? Is it as simple as just owning a dog of that breed?

In most cases if you own or have owned a dog of the breed you would be classified as a specialist - if you have never lived with the breed then you are not considered to be a breed specialist.

But it is up to the breed club compiling the list so they may add other things such as having had the breed for a certain number of years or to have shown or bred them.