They should really have learned their lesson by now. Andrew Mitchell yesterday became the latest senior figure to be photographed leaving Downing Street clutching sensitive Government documents in clear view of the waiting photographers.
Following in the footsteps of Caroline Flint, Danny Alexander and Metropolitan Police commander Bob Quick, Mr Mitchell was undone by the oldest trick of the modern digital camera: the ability to capture even the smallest print from yards away.
The International Development Secretary was shown leaving a National Security Council meeting yesterday morning with briefing notes on Afghanistan marked "protected".
The document made explicit the Government's delight at the impending departure of Afghan President Hamid Karzai and described British attitudes to criticism of the country's banking system by the IMF.
Confirming that the Government is pleased Mr Karzai is intending to stand down after two terms in office in 2014, the document reads: "This is very important. It improves Afghanistan's political prospects very significantly. We should welcome Karzai's announcement in public and in private."
The document also details Government concern, highlighted repeatedly by various international organisations in recent months, that foreign aid given to Afghanistan is sent to a finance ministry and banking sector that is notoriously corrupt. Some international funds to Afghanistan have been suspended, but the document suggests that this may destabilise transitional arrangements for handing over more power to the Afghan authorities.
Mr Mitchell's briefing document reads: "The World Bank have told us that the suspension of UK and other donor funds to the Afghan government will soon begin to destabilise activities essential for transition." The document adds that in the autumn the IMF will send a new inspection team to assess whether the situation has improved.
It continues: "We are hopeful that the government will have demonstrated sufficient progress towards credible reforms of the financial sector, and actions to address the Kabul bank fraud so that a new programme can be agreed over the autumn." Mr Mitchell apparently realised he had mistakenly displayed the confidential briefing papers but told an aide: "It is nothing top secret."
The Department for International Development later said the papers were "of a routine nature". A spokesman said: "They would have had a national security level marking of 'restricted' or 'confidential' if they contained anything of significant sensitivity."
Mr Mitchell could at least console himself that he is far from the first to be caught out like this. Former housing minister Ms Flint was snapped in 2008 carrying papers warning of a property crisis which could see house prices fall by 10 per cent, while last November Mr Alexander was pictured with a copy of the Government's spending review document, revealing a potential 490,000 public sector job losses.
The only person to lose their job was Met Assistant Commissioner Bob Quick, who was snapped with a briefing of an ongoing counter-terrorism operation. Some raids had to be brought forward as a result and Mr Quick resigned.