It would be a career ending move if they got caught.
Yes indeed but, the leaking ship that is 'Whitehall', seems to not catch 'n' fire on them on the same scale as the leaking. Also the forth Estate is rarely one to address issues, without inserting its own agenda.
Personally I in the first instance never trust leakers and see them in the same boat as un-named sources, which I have little doubt are predominately made up.
Similarly those who 'leak' rather than use the Chain of Command, to whistle blow. I sometimes feel are more chasing their own agenda, within the internal 'Chain of Command'. While I acknowledge at times which may need that need addressing by the external 'Chain of Command.