Dr. Simon Longstaff of the St. James Ethics Centre has an article on ministerial responsibility in the Centre’s just published winter edition of Living Ethics. He reminds us that when Winston Churchill famously and publicly apologised for his failures that lead to the fall of Singapore, there were three not two elements: “I did not know. I was not told. I should have asked”.
Dr. Longstaff says that Churchill got it right in stipulating that a minister's responsibility is not only to listen, but to ask when inquiry should be made. Those who think two out of three is sufficient compliance with the standard are failing in their duty.
I guess you would take with a grain of salt the observation that "tactical ignorance" is now part of the modus operandi at the highest levels of government if anyone other than the Director of the St. James Ethics Centre told you so. Dr. Longstaff concludes
“The natural tendency for self preservation…..has seen ministers develop innovations such as the most recent attempt to record ignorance. I’m told that, at the Commonwealth level at least, files sent to ministers can now be marked officially as “Not Read by the Minister”Even the strictest laws on public accountability can't cope with this sort of practice.