Reluctance to reveal secret intelligence has always caused problems for government, tied their hands, limited their ability to achieve desirable ends.
In November 1867, when England was panicked by Fenians, Continental revolutionaries & home grown working class radicals, the Home Secretary proposed a recall of Parliament to introduce gun control laws.
Cabinet were not persuaded. Among other objections, the Prime Minister, Lord Derby, pointed out that Parliament could not be persuaded to vote for any limit on the right to possess arms unless the Home Secretary revealed secret intelligence he had received from one Emile Van Quellin, a Swiss-American living near Bern, about a supposed alliance of these revolutionaries.
It is not altogether clear whether the reluctance to reveal this intelligence lay more in a desire to protect the source, reluctance to reveal that the British government was indulging in morally distasteful espionage, or a fear of being laughed at.
