You’d be forgiven for not knowing that the Australian Greens almost pulled off an audacious coup on the final day of this week’s parliamentary session.

If it wasn’t for another government backbencher, George Christensen, the Greens would have moved an important step closer to establishing a “commission of inquiry” into the banking sector.

Given that only the government can establish an actual royal commission, this would have been the next-closest thing. In some ways it would have been better because the inquiry would report its finding to the Parliament, not government.

After successfully passing legislation in the Senate on Wednesday to create the commission, the Greens teamed with Labor and the former Nationals MP Bob Katter in an attempt to force the House of Representatives to debate the bill on August 14. This wouldn’t have guaranteed the legislation would be passed, but it would have been a symbolic win for the pro-RC forces and increased pressure on the Coalition to reverse its opposition to a royal commission.

However, it was Mr Christensen who reversed his position, backing down from an oft-repeated promise to cross the floor against the government if he ever got a chance to support the establishment of an RC.

Instead, Mr Christensen sat grumpily with government MPs when it came time to vote, with his National Party leader Barnaby Joyce on one side, seemingly prepared to stop the backbencher if he showed signs of bolting over to Labor, while Treasurer Scott Morrison sat on the other.

Labor leader Bill Shorten produced one of his better zingers to castigate the not-so-rogue MP, scoffing that Mr Christensen had proven to be a “lion in [his home town of] Mackay, but a mouse in Canberra”.

And so the attempt failed, and the Greens will no doubt regroup to devise new tactics.

It should be remembered that although many have tried to lay claim to the idea, it was the Greens that first proposed that a banking royal commission. Then Labor sniffed a populist opportunity and latched onto the idea, giving voters the impression that all their banking grievances would miraculously be resolved with such an inquiry.

The Turnbull government lost a lot of skin defending the banks against an RC. In an attempt to be seen to be doing something about their bad behaviour, the government announced the banks would be called to Canberra on an annual basis to face questioning from a parliamentary committee.

It’s true that even the most senior of departmental officials become nervous at the prospect of being grilled by a bunch of parliamentarians. But for business-hardened banking executives, the threat of such an ordeal was no more terrifying than the promise of being whipped with a feather.

So after agreeing to annually subject themselves to a severe reprimand, the banks were left reasonably confident that PM Turnbull would continue to be their human shield. In order to deal with the real threat – Labor’s support for an RC – they installed former Labor state premier Anna Bligh as the head of their lobby group, confident she was their best chance for changing the Opposition’s mind.

Both of these were serious misjudgements by the big bank chiefs, who discovered when a $6 billion bank levy was announced on budget night that they weren’t as untouchable as they thought. Now the banks are fighting on two fronts: against a levy and a royal commission.

While the levy is a done deal (according to Labor), an inquiry seemed unlikely until the Greens’ unexpected manoeuvre.

This week ended with the banks lining up to bleat about their impoverished circumstances to the parliamentary committee considering the legislation to create the bank levy. Their pleas will likely go unheeded, given the vast majority of voters support the levy even though they assume the banks will simply pass it on to customers.

The scramble to keep George Christensen in his seat suggests the Turnbull government is not yet so enamoured with Labor-lite policies that it’s prepared to give the Opposition (and the Greens) a win by acceding to an RC.

But only a fool would assume that a PM desperate to increase his approval ratings wouldn’t seriously consider doing so by giving the bank-bashing voters exactly what they want.