Every cabinet suffers the occasional leak, but only in Australia has the leaking come from the cabinets themselves. The filing cabinets that is. Two of them.

The cabinets were somewhere in Australia’s Parliament House and had been deemed surplus. This was probably because the keys had become lost, and what’s the point of a filing cabinet without a key?

As is customary, government furniture which is no longer required is sold off to the local community in Canberra, using a second-hand furniture store. But the locked filing cabinets were still full of documents. No one, it seems, thought to check what might be making the cabinets so heavy.

This week the answer emerged: ten years of top secret cabinet discussions, covering the work of five governments. Among the material: Stories intensely embarrassing for the Australian Federal Police, for the current treasurer Scott Morrison, and for the former prime minister Kevin Rudd, who has already commenced legal action.

The Australian Broadcasting Corporation (ABC), without disclosing its source, began doling out its scoops late last week. There was fevered speculation about who was supplying such a spectacular series of leaks. A disgruntled minister? A public servant gone wild? On Wednesday morning, ABC published a fresh series of revelations, this time explaining the source. A member of the public had bought the filing cabinets. The person had kept them for some time and then used a drill to remove the locks. That’s when the buyer came across the documents — most of them marked “Top Secret” and “AUSTEO,” meaning “for Australian Eyes Only.” He gave them to ABC.

The ABC has published nine stories based on the documents, but said other documents were too sensitive for publication because of national security concerns. That revelation only added to the concern about the initial sale of the unchecked filing cabinets. After all, the sale of government furniture was not limited to Australians. Anyone could have made a purchase, in theory, handing the contents to a foreign agent or government.

Adding to the pressure, the government is currently considering new laws designed to clamp down on foreign influence in Australian politics. Australia’s major media companies believe journalists will become the unintended targets of the new laws — facing prosecution if they accept leaked documents. Even if, as in this case, the leak is more a case of deep drawers, rather than Deep Throat.

Has this happened anywhere else? I can only think of Britain where, during the 1990s, they had a system under which diplomatic bags were washed at the laundry of Wandsworth prison. On one occasion, in 1991, Canada’s diplomatic bags were mistakenly sent there too — all full of top-secret NATO documents — which promptly went missing.

Meanwhile, back in Australia, there’s a standoff between the ABC and the Australian Security Intelligence Organization (ASIO). With the broadcaster’s permission, ASIO officers visited ABC premises in Canberra and Brisbane early on Thursday.

They dropped off special safes so that the documents could be properly secured, while agreeing that ABC would retain access. Later, after further negotiation, the ABC handed over the documents to ASIO. According to both the government and the ABC: “This has been achieved without compromising the ABC’s priority of protecting the integrity of its source and its reporting, while acknowledging the Commonwealth’s national security interests.”

Meanwhile, there have been reports of “chatter” among Australia’s Five Eyes intelligence partners — the United States, Britain, Canada and New Zealand — about the security breach. One member of parliament, Andrew Wilkie, who is a former intelligence analyst, has been among the most critical of the lapse: “It sends a signal to our intelligence partners and allies that Australia might not be trustworthy when it comes to sharing information and intelligence with us.”

And where are the documents now? Presumably in a fresh filing cabinet. We can only hope no one loses the keys.