If the government ends up convincing enough crossbench senators to wave through its soon-to-be $80 billion company tax cut package, it will be no thanks to the Business Council of Australia, which has shown a particular maladroitness in its campaigning for the handout.

Yesterday Grant King and Jennifer Westacott again attended a hearing of the senate inquiry into the BCA’s commitment to the senate that companies would “commit to invest more in Australia which will lead to employing more Australians and therefore stronger wage growth as the tax cut takes effect.” Another Business council figure, Andrew Bragg, formerly of big bank front group the Financial Services Council, then acting Liberal Party director, joined by phone, when it actually worked. As Myriam Robin noted, at least they fronted, unlike most of the signatories to the commitment.

Tuesday’s inquiry hearing had elicited a peculiar moment when the Greens’ Lee Rhiannon asked the BCA “Can you give us an example of another country where tax cuts have resulted in wage rises?” to which Westacott replied “Ah, we will take that on notice.” For nearly two years, both the BCA and the government have claimed that company tax cuts lead to stronger wage growth. Given a number of countries around the world have reduced company tax rates in recent years, finding an example where wage growth has strengthened following tax cuts should be fairly straightforward. And given Labor’s Kristina Keneally, who is on this committee, literally asked Grant King the exact same question on Sky back in late 2016, it’s extraordinary that Westacott didn’t know that she’d be asked that question and have an answer ready to hand.

Well, extraordinary if the claim is true. But it’s very difficult to find any country where company tax cuts in recent years have produced wage rises. But it’s very easy to find countries where company tax cuts have preceded either wage falls or periods where wages underperformed Australia, where we haven’t reduced company taxes. As Crikey has endlessly pointed out, real wages in the UK have fallen for much of the last decade despite big company tax cuts started by the Brown government and continued by the Cameron government. And Canadian wages have also fared poorly compared to wages in Australia despite company tax cuts there and a mining investment boom of the kind we also enjoyed.

Perhaps, knowing they didn’t have an answer, the BCA always planned to take the question on notice. But then, strangely, the Council provided an answer at yesterday’s hearing, tabling a two-page document that referred to Treasury’s modelling of the (negligible) impacts of the proposed tax cut, and citing four studies that showed, or relied on modelling to show, the link between company tax increases and lower wages. The only reference to a lower tax rate was an OECD study claiming higher productivity from lower company tax rates (although alas, UK productivity growth has slumped in the wake of tax cuts) and from another study based on the argument that much of the burden of company taxes falls on workers. That’s at odds with bodies like the US Congressional Budget Office and US Treasury, which assume the bulk of the burden of company taxes falls on capital. Well, that was US Treasury’s view until Trump’s Treasury Secretary Steve Mnuchin forced it to take the relevant study down.

Since no one is talking about lifting the company tax rate, we’re still left with the question that the BCA, and spruikers of the company tax cut within the government, and cheerleaders like the Financial Review’s Aaron Patrick have been unable to answer: what evidence do they have from the real world of the benefits of company tax cuts?

Another thing to emerge from yesterday’s hearing — bizarrely absent from Patrick’s account — is that Westacott and King last year met with Cambridge Analytica, although they decided not to engage that troubled firm. Why, one wonders, did the BCA want to discuss the services of a company best known for shameless exploitation of private information for the purposes of manipulating voters? Did they not have enough confidence in the strength of their case? Given their inept presentation of it, maybe they were right to seek help from what is now one of the most tarnished names in global business.