Criminal prosecutions seem initially attractive
Of course the Opposition will make the kinds of pronouncements to appeal to the wild-eyed, drooling Daily Mail readers. There is unfortunately, a real differences between corporate responsibility of directors (of limited liability corporations) to their shareholders for proper governance and some sort of analogue being drawn with Governement Ministers and their senior civil servant executives. The Ministers and senior execs FEEL NOTHING when these breaches arise.
Now, if Ms Smith (or Blears, or Mr Browne, or...) were poked in the eye with a sharp stick each time they, or any employee in their department, caused a breach, then some performance improvement might follow. There is no point pursuing prosecution for these acts of omission and commission - we have to make it HURT those responsible.
Better, each time a Minister makes a fatuous & ignorant statement, at the despatch box or in an interview, press conference - whatever - i.e. "in a secure form, but was downloaded " or "but a department official emailed it to me, I didn't take it out of the department" then they should be poked in both eyes with 2 sharp sticks.
Depending on the efficacy of their remaining vision, I am convinced beyond all doubt that Ministers would soon be poking senior execs in their eyes. Then the message that security breaches hurt would be real for thee people and Departmental enforcement of EXISTING POLICY would be stepped up, pretty swiftish.