As Malcolm Turnbull returns, no doubt reluctantly, from the photo-ops of Europe to the harsh world of Australian politics, he is inevitably turning his mind to the need to vaporise Bill Shorten.

And it will not be enough to simply keep repeating the line about “my taxes down, his taxes up”. This is especially the case as it seems certain that Labor will be able to afford bigger personal income tax cuts than the Coalition can, by paying for them through the removal of perks, subsidies and other entitlements dispersed in the prodigal Howard years.

So the killing of Bill needs to be more immediate and direct, and one way to start administering the poison is by highlighting the Opposition leader’s background as a union apparatchik.

Shorten, declares the Liberal Party, was a union organiser and he wants to be a union prime minister. Enough said.

It is true that the unions, and in particular the CFMMEU, the government’s favourite whipping boy, are not popular, and Shorten’s association with the movement is probably a net political minus for him.

But it could be worse; he could be tainted with being involved with banking. Which leads to the immediate rejoinder to the Liberal Party’s argument: Turnbull was a merchant banker and he has now become a bankers’ prime minister.

Since he became prime minster – long before, in fact – Turnbull has been a zealous defender and protector of the four pillars and everything they stand for. He opposed Labor’s early reforms to demand that financial institutions – principally the banks and their subsidiaries – behave honestly and decently. Turnbull claimed it would involve excessive regulation and red tape.

When it became obvious that honesty and decency were not always priorities, Turnbull effectively said that it didn’t really matter – there may have been a few rotten apples, but the orchard was still producing for Australia, a few tweaks would fix things. When the malfeasance continued and increased, Turnbull said that a friendly chat between the moguls and some politicians was all that was required to repair the culture.

But a serious inquiry, a royal commission? Out of the question: royal commissions were for the enemy – the unions, the traditional opponents of the banks since the 19th century. The banks were our mates and always have been – that’s why we’re giving them more than $13 billion in tax cuts. Government by the bankers, for the bankers, and, in Turnbull’s case, of the bankers.

Given the events of the last few weeks and those of many months to come, bankers’ buddy may not be the image our prime minister wants to take into a tight election. But it is the one he has made for himself, and any attempts to change it have proven futile.

Indeed, given the rest of his CV, it could be hard to make serious improvements. In other facets of his previous life Malcolm Turnbull was (and basically still is) a lawyer, not the most loved of professions. But this is arguably better than another of his early forays: he was a journalist.

Now that really is the pits. Perhaps he is wise to stick to banking after all, with all its fraud, theft, perjury and general bastardry.