[retree]

DA notices aren't legally enforceable though. Most newspapers comply voluntarily.

They're overseen by a committee of both government representatives and those from the press and news distribution (including Google's Europe head of PR)

see http://www.dnotice.org.uk/

[scraplab]

Perhaps, but given their sensitivity you would want to comply or face some difficult discussions with intelligence agencies.

[calpaterson]

They may not be enforceable by the letter of the law, they aren't quite as "advisory" as the name would imply.