Correction...
Government data rules mean that RESTRICTED documents do have to be shredded.
Holding NATO RESTRICTED on unaccredited information systems is still a breach of the Official Secrets Acts, even though anything marked as such is pretty openly shareable within the military community.....
So the Sun and NI (not being in the military community) are breaking the official secrets act, and hence both people tracked to having them, reading them and their organisation's information owner can still be arrested and done from at most treason.....
And the official government classification labels are actually:
Unclassified
Protect
Restricted
Confidential
Secret
Top Secret
J