That seemed pretty black and white: there was no requirement to activate the citizenship, it was automatic. So at 12.31pm on Monday, August 7, I sent Joyce's media adviser, Jake Smith, an email entitled: "Is the boss a Kiwi?" I set out a series of questions based on what I'd found. During a subsequent phone call, Jake was dismissive. We've had all these questions before, he said, but there's nothing to see here. The NZ authorities have told us we don't have a problem, Barnaby established that many years ago. I wasn't convinced. I dug some more and found a number of places where the New Zealand Department of Internal Affairs (DIA) said citizenship by descent was automatic, and registration was only needed if you wanted a passport. I went to the New Zealand high commission and the DIA and put to them a "hypothetical scenario" because they would not comment on specific cases. I pressed them repeatedly for a response but they did not answer.

At this point I decided I needed some extra firepower and brought colleague Amy Remeikis on board. I ran her through it and she agreed - there was something here. So we decided to ask some experts. George Williams and Anne Twomey, Australia's top constitutional experts, were the logical choice. Both agreed that Joyce could be in trouble, but cautioned they were not experts on New Zealand law. We found Anna Hood at the University of Auckland, an international law expert who had written a paper on New Zealand citizenship. She too agreed: at the very least Barnaby had a case to answer. Satisfied we had something, we went back to Smith in Joyce's office at 1.39pm on Thursday, August 10.

"We have done some more digging, we have spoken to NZ authorities and we have obtained advice from three leading experts. Based on all this, we believe there are some open questions here - and we believe we have enough to write a story saying as much," we emailed. "Our advice is that any person born to a Kiwi father between 1949 and 1978 automatically became an NZ citizen by descent. There is a further process you can go through to register that citizenship - the process that confers the rights such as passports etc. But even if that citizenship is never registered, the person is still an NZ citizen." We now know that August 10 was when the government started discussing this looming bombshell with the Solicitor-General. But Smith told us he would only respond to an on-the-record response from the New Zealand high commission. We explained they hadn't given us one yet but we still believed the story was strong enough run. Ultimately, we decided to give Smith and Joyce some more time: it's a big thing to accuse the Deputy Prime Minister of potentially being ineligible to sit in the Parliament.

But first thing on Monday - at 7.56am - we told Smith his time was up. We were ready to write. Loading The story was just about ready to go when Joyce got to his feet in the House of Representatives to tell a stunned Parliament he may be a dual citizen and would refer himself to the High Court. After repeatedly ignoring us and obfuscating, he finally confessed.