Seven weeks ago Labor launched a strong attack in parliament on prime minister Malcolm Turnbull for his decision to invest part of his personal wealth in the Cayman Islands. As a political strategy it looked like a flop: the attack made no immediate dent in Turnbull’s approval ratings and earned Labor no praise from the commentariat. If anything, in the short term, the Cayman Islands question time strategy seemed to ricochet on the opposition, inflicting more damage on Bill Shorten than Malcolm Turnbull.

It was important for Labor to launch the Cayman attack on Turnbull. Labor supporters needed to see that the opposition was unafraid to take on the new prime minister. And despite the initial blowback, the reality is that Labor planted a seed of doubt about Turnbull in many people’s minds. But they cooked the frog too quickly, and it jumped out of the pan.

The past two weeks indicate that Labor learned from their Cayman experience how to better use parliament, and particularly question time, to expose deficiencies in Turnbull and his government.

When it first emerged that the Australian Federal Police were investigating special minister for state Mal Brough the opposition barely said a word. On 17 November it was revealed that the AFP were seeking to determine if Brough “counselled and procured” a former staffer to Peter Slipper, James Ashby, to access restricted data (Slipper’s diaries); two days later Brough confirmed the police had raided his home.

Even though Brough now administers the act under which parliamentary staff are employed, no Labor frontbencher jumped up and demanded Turnbull immediately stand Brough aside. Instead, Labor backbencher Graham Perrett simply issued a statement saying that Brough needed to explain himself.

For a week it appeared that the Brough story was going nowhere in particular. When parliament resumed on 23 November, Labor waited until its seventh question in question time to ask about Brough and the diaries. None of three questions put by shadow attorney general Mark Dreyfus that day called for Brough to stand aside.

Rather the questions laid the foundation for Labor’s subsequent pursuit of Brough and Turnbull for the next two weeks: that Brough could be asked questions about this matter because of his responsibilities as special minister for state; that Brough had admitted to Channel 9 that he committed the act that sat at the heart of the AFP’s investigation; and that Malcolm Turnbull owned the Brough problem because he brought Brough back to cabinet in that particular role.

Throughout the week, Labor’s headline questions in parliament were about the economy, taxation, climate change and domestic violence. It almost seemed like the opposition’s questions about Brough – always at the end of question time – were either an afterthought or a fishing expedition. Over the next few days, Brough and Turnbull gave short, seemingly unremarkable answers.

Yet Labor’s questions were written in such a manner as to slowly and credibly build a case. The opposition put questions deliberately crafted with a view to eliciting certain information from Brough. By doing so, Labor could claim in future questions that Brough had previously relied on such information and argue their questions were in order.

It worked: Speaker Tony Smith allowed almost every one of the opposition’s questions to Brough. Dreyfus’s slow, calm and focused style was also deliberate. Manufactured political outrage is easy to mock or ignore, but a determined and serious demeanour through repeated questioning is not. It was designed to unnerve Brough. It did.

On the final sitting day of that week – and the day before Turnbull flew out to the climate change talks in Paris – Labor escalated its attack. All of Labor’s questions were about the special minister for state. Brough’s anger and impatience started to get the better of him and his answers began to drift off-script.

Shorten put the final question of the day to Turnbull and included a reference to Tony Abbott to boot, knowing that it would provoke the increasingly vocal discontented rightwing rump on Turnbull’s back bench. It was a near-perfect taunt to Turnbull: with a minister under investigation and enemies attacking from within, well, what a great time to leave the country!

Truth be told, the opposition had little information to work with heading into Monday and Tuesday, but Labor continued the approach from the previous week. It backed up its questions with matters of public importance (MPI) debates each day.

With the prime minister overseas, and no one else on the government front bench appearing to assist the special minister for state, it seemed likely that Brough would eventually make a mistake. By Tuesday he did, stating that the question 60 Minutes reporter Liz Hayes put to him on air – “Did you ask James Ashby to procure copies of Peter Slipper’s diary for you?” – was not the “full question”, thereby giving an impression that some other inference might be drawn from his answer, “Yes I did.”

Mal Brough is in serious strife.

It was the error for which Labor had waited. That night Laurie Oakes released the transcript on Channel 9, showing that reporter Liz Hayes merely stumbled her words at the beginning of the question, and Oakes tore into Brough. By the next morning, Brough was apologising in parliament for “unwittingly” creating confusion.

Labor had enough right there to charge Brough with misleading the parliament, but an angry and frustrated Brough managed to prove the old adage “given enough rope, he will hang himself.” Labor put the exact Liz Hayes question to Brough in question time and he contradicted himself by answering “no”. The temptation for Labor to lead off its attack a week earlier with this tactic was almost irresistible, but the opposition held it back until Brough was really rattled and the question could be used to its most devastating effect.

Labor made lots of tough calls during the past two weeks: not to rush to demand Brough’s head until the case had been made; to set aside – for the time being – other juicy stories of ministers acting extravagantly or misleading the house; to focus on more on Brough and not on Wyatt Roy and Christopher Pyne, both named in the AFP search warrants; to let internal battles within the Liberal party largely speak for themselves; and to continue to push policy arguments.

The strategy against Brough paid off with a further unexpected dividend when Ian Macfarlane bolstered the “government under seige” narrative by announcing his defection from the Liberals to the Nationals to get himself back into cabinet. Adult government indeed.

Mal Brough is in serious strife. The government chose to gag each one of Labor’s five censure motions rather than stand and defend Brough. Across three MPI debates about Brough, most government MPs refused to even say his name. Throughout the two weeks of questioning, government members had 20 opportunities to defend Brough but could not bring themselves to do so.

It’s hard to see how Brough survives as a minister. But Labor has achieved more than just damaging the special minister for state. The opposition also demonstrated that Turnbull’s team is pretty lousy at crisis management, and exposed Turnbull, who likes to cast himself as the anti-politician, as the kind of guy who will do questionable deals – in this case giving Brough a ministry in exchange for his support in the leadership ballot – to get himself into power. The latest Newspoll shows that some of the sheen has come off Turnbull, with satisfaction in his performance falling eight points.

The other reveal in the past two weeks is Shorten’s comfort with a strong team approach. True, a leader probably shouldn’t lead the charge in a situation like this, and unlike the Cayman attack, Shorten didn’t. Shorten, Chris Bowen and Tanya Plibersek kept a focus on policy issues while Dreyfus, Tony Burke and Anthony Albanese kept the drum beat on Brough going.

Shorten’s style of leadership empowers the team around him. It’s a good contrast with the egocentric Turnbull, whose battle-weary MPs most likely eagerly left for their summer holidays grateful to get a break from infighting and division.

It may be the best time ever to be an Australian, but after the last two weeks in parliament, it certainly isn’t the greatest time ever right now to be a Liberal MP.